curl(1) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | URL | OUTPUT | PROTOCOLS | PROGRESS METER | OPTIONS | FILES | ENVIRONMENT | PROXY PROTOCOL PREFIXES | EXIT CODES | AUTHORS / CONTRIBUTORS | WWW | SEE ALSO | COLOPHON

curl(1)                        Curl Manual                       curl(1)

NAME         top

       curl - transfer a URL

SYNOPSIS         top

       curl [options / URLs]

DESCRIPTION         top

       curl is a tool to transfer data from or to a server, using one of
       the supported protocols (DICT, FILE, FTP, FTPS, GOPHER, HTTP,
       HTTPS, IMAP, IMAPS, LDAP, LDAPS, MQTT, POP3, POP3S, RTMP, RTMPS,
       RTSP, SCP, SFTP, SMB, SMBS, SMTP, SMTPS, TELNET and TFTP). The
       command is designed to work without user interaction.

       curl offers a busload of useful tricks like proxy support, user
       authentication, FTP upload, HTTP post, SSL connections, cookies,
       file transfer resume and more. As you will see below, the number
       of features will make your head spin!

       curl is powered by libcurl for all transfer-related features. See
       libcurl(3) for details.

URL         top

       The URL syntax is protocol-dependent. You'll find a detailed
       description in RFC 3986.

       You can specify multiple URLs or parts of URLs by writing part
       sets within braces and quoting the URL as in:

         "http://site.{one,two,three}.com"

       or you can get sequences of alphanumeric series by using [] as
       in:

         "ftp://ftp.example.com/file[1-100].txt"

         "ftp://ftp.example.com/file[001-100].txt"    (with leading
       zeros)

         "ftp://ftp.example.com/file[a-z].txt"

       Nested sequences are not supported, but you can use several ones
       next to each other:

         "http://example.com/archive[1996-1999]/vol[1-4]/part{a,b,c}.html"

       You can specify any amount of URLs on the command line. They will
       be fetched in a sequential manner in the specified order. You can
       specify command line options and URLs mixed and in any order on
       the command line.

       You can specify a step counter for the ranges to get every Nth
       number or letter:

         "http://example.com/file[1-100:10].txt"

         "http://example.com/file[a-z:2].txt"

       When using [] or {} sequences when invoked from a command line
       prompt, you probably have to put the full URL within double
       quotes to avoid the shell from interfering with it. This also
       goes for other characters treated special, like for example '&',
       '?' and '*'.

       Provide the IPv6 zone index in the URL with an escaped percentage
       sign and the interface name. Like in

         "http://[fe80::3%25eth0]/"

       If you specify URL without protocol:// prefix, curl will attempt
       to guess what protocol you might want. It will then default to
       HTTP but try other protocols based on often-used host name
       prefixes. For example, for host names starting with "ftp." curl
       will assume you want to speak FTP.

       curl will do its best to use what you pass to it as a URL. It is
       not trying to validate it as a syntactically correct URL by any
       means but is instead very liberal with what it accepts.

       curl will attempt to re-use connections for multiple file
       transfers, so that getting many files from the same server will
       not do multiple connects / handshakes. This improves speed. Of
       course this is only done on files specified on a single command
       line and cannot be used between separate curl invokes.

OUTPUT         top

       If not told otherwise, curl writes the received data to stdout.
       It can be instructed to instead save that data into a local file,
       using the -o, --output or -O, --remote-name options. If curl is
       given multiple URLs to transfer on the command line, it similarly
       needs multiple options for where to save them.

       curl does not parse or otherwise "understand" the content it gets
       or writes as output. It does no encoding or decoding, unless
       explicitly asked so with dedicated command line options.

PROTOCOLS         top

       curl supports numerous protocols, or put in URL terms: schemes.
       Your particular build may not support them all.

       DICT   Lets you lookup words using online dictionaries.

       FILE   Read or write local files. curl does not support accessing
              file:// URL remotely, but when running on Microsoft
              Windows using the native UNC approach will work.

       FTP(S) curl supports the File Transfer Protocol with a lot of
              tweaks and levers. With or without using TLS.

       GOPHER Retrieve files.

       HTTP(S)
              curl supports HTTP with numerous options and variations.
              It can speak HTTP version 0.9, 1.0, 1.1, 2 and 3 depending
              on build options and the correct command line options.

       IMAP(S)
              Using the mail reading protocol, curl can "download"
              emails for you. With or without using TLS.

       LDAP(S)
              curl can do directory lookups for you, with or without
              TLS.

       MQTT   curl supports MQTT version 3. Downloading over MQTT equals
              "subscribe" to a topic while uploading/posting equals
              "publish" on a topic. MQTT support is experimental and TLS
              based MQTT is not supported (yet).

       POP3(S)
              Downloading from a pop3 server means getting a mail. With
              or without using TLS.

       RTMP(S)
              The Realtime Messaging Protocol is primarily used to
              server streaming media and curl can download it.

       RTSP   curl supports RTSP 1.0 downloads.

       SCP    curl supports SSH version 2 scp transfers.

       SFTP   curl supports SFTP (draft 5) done over SSH version 2.

       SMB(S) curl supports SMB version 1 for upload and download.

       SMTP(S)
              Uploading contents to an SMTP server means sending an
              email. With or without TLS.

       TELNET Telling curl to fetch a telnet URL starts an interactive
              session where it sends what it reads on stdin and outputs
              what the server sends it.

       TFTP   curl can do TFTP downloads and uploads.

PROGRESS METER         top

       curl normally displays a progress meter during operations,
       indicating the amount of transferred data, transfer speeds and
       estimated time left, etc. The progress meter displays number of
       bytes and the speeds are in bytes per second. The suffixes (k, M,
       G, T, P) are 1024 based. For example 1k is 1024 bytes. 1M is
       1048576 bytes.

       curl displays this data to the terminal by default, so if you
       invoke curl to do an operation and it is about to write data to
       the terminal, it disables the progress meter as otherwise it
       would mess up the output mixing progress meter and response data.

       If you want a progress meter for HTTP POST or PUT requests, you
       need to redirect the response output to a file, using shell
       redirect (>), -o, --output or similar.

       It is not the same case for FTP upload as that operation does not
       spit out any response data to the terminal.

       If you prefer a progress "bar" instead of the regular meter, -#,
       --progress-bar is your friend. You can also disable the progress
       meter completely with the -s, --silent option.

OPTIONS         top

       Options start with one or two dashes. Many of the options require
       an additional value next to them.

       The short "single-dash" form of the options, -d for example, may
       be used with or without a space between it and its value,
       although a space is a recommended separator. The long "double-
       dash" form, -d, --data for example, requires a space between it
       and its value.

       Short version options that don't need any additional values can
       be used immediately next to each other, like for example you can
       specify all the options -O, -L and -v at once as -OLv.

       In general, all boolean options are enabled with --option and yet
       again disabled with --no-option. That is, you use the exact same
       option name but prefix it with "no-". However, in this list we
       mostly only list and show the --option version of them. (This
       concept with --no options was added in 7.19.0. Previously most
       options were toggled on/off on repeated use of the same command
       line option.)

       --abstract-unix-socket <path>
              (HTTP) Connect through an abstract Unix domain socket,
              instead of using the network.  Note: netstat shows the
              path of an abstract socket prefixed with '@', however the
              <path> argument should not have this leading character.

              Added in 7.53.0.

       --alt-svc <file name>
              (HTTPS) WARNING: this option is experimental. Do not use
              in production.

              This option enables the alt-svc parser in curl. If the
              file name points to an existing alt-svc cache file, that
              will be used. After a completed transfer, the cache will
              be saved to the file name again if it has been modified.

              Specify a "" file name (zero length) to avoid
              loading/saving and make curl just handle the cache in
              memory.

              If this option is used several times, curl will load
              contents from all the files but the last one will be used
              for saving.

              Added in 7.64.1.

       --anyauth
              (HTTP) Tells curl to figure out authentication method by
              itself, and use the most secure one the remote site claims
              to support. This is done by first doing a request and
              checking the response-headers, thus possibly inducing an
              extra network round-trip. This is used instead of setting
              a specific authentication method, which you can do with
              --basic, --digest, --ntlm, and --negotiate.

              Using --anyauth is not recommended if you do uploads from
              stdin, since it may require data to be sent twice and then
              the client must be able to rewind. If the need should
              arise when uploading from stdin, the upload operation will
              fail.

              Used together with -u, --user.

              See also --proxy-anyauth, --basic and --digest.

       -a, --append
              (FTP SFTP) When used in an upload, this makes curl append
              to the target file instead of overwriting it. If the
              remote file doesn't exist, it will be created.  Note that
              this flag is ignored by some SFTP servers (including
              OpenSSH).

       --aws-sigv4 <provider1[:provider2[:region[:service]]]>
              Use AWS V4 signature authentication in the transfer.

              The provider argument is a string that is used by the
              algorithm when creating outgoing authentication headers.

              The region argument is a string that points to a
              geographic area of a resources collection (region-code)
              when the region name is omitted from the endpoint.

              The service argument is a string that points to a function
              provided by a cloud (service-code) when the service name
              is omitted from the endpoint.

              Added in 7.75.0.

       --basic
              (HTTP) Tells curl to use HTTP Basic authentication with
              the remote host. This is the default and this option is
              usually pointless, unless you use it to override a
              previously set option that sets a different authentication
              method (such as --ntlm, --digest, or --negotiate).

              Used together with -u, --user.

              See also --proxy-basic.

       --cacert <file>
              (TLS) Tells curl to use the specified certificate file to
              verify the peer. The file may contain multiple CA
              certificates. The certificate(s) must be in PEM format.
              Normally curl is built to use a default file for this, so
              this option is typically used to alter that default file.

              curl recognizes the environment variable named
              'CURL_CA_BUNDLE' if it is set, and uses the given path as
              a path to a CA cert bundle. This option overrides that
              variable.

              The windows version of curl will automatically look for a
              CA certs file named ´curl-ca-bundle.crt´, either in the
              same directory as curl.exe, or in the Current Working
              Directory, or in any folder along your PATH.

              If curl is built against the NSS SSL library, the NSS PEM
              PKCS#11 module (libnsspem.so) needs to be available for
              this option to work properly.

              (iOS and macOS only) If curl is built against Secure
              Transport, then this option is supported for backward
              compatibility with other SSL engines, but it should not be
              set. If the option is not set, then curl will use the
              certificates in the system and user Keychain to verify the
              peer, which is the preferred method of verifying the
              peer's certificate chain.

              (Schannel only) This option is supported for Schannel in
              Windows 7 or later with libcurl 7.60 or later. This option
              is supported for backward compatibility with other SSL
              engines; instead it is recommended to use Windows' store
              of root certificates (the default for Schannel).

              If this option is used several times, the last one will be
              used.

       --capath <dir>
              (TLS) Tells curl to use the specified certificate
              directory to verify the peer. Multiple paths can be
              provided by separating them with ":" (e.g.
              "path1:path2:path3"). The certificates must be in PEM
              format, and if curl is built against OpenSSL, the
              directory must have been processed using the c_rehash
              utility supplied with OpenSSL. Using --capath can allow
              OpenSSL-powered curl to make SSL-connections much more
              efficiently than using --cacert if the --cacert file
              contains many CA certificates.

              If this option is set, the default capath value will be
              ignored, and if it is used several times, the last one
              will be used.

       --cert-status
              (TLS) Tells curl to verify the status of the server
              certificate by using the Certificate Status Request (aka.
              OCSP stapling) TLS extension.

              If this option is enabled and the server sends an invalid
              (e.g. expired) response, if the response suggests that the
              server certificate has been revoked, or no response at all
              is received, the verification fails.

              This is currently only implemented in the OpenSSL, GnuTLS
              and NSS backends.

              Added in 7.41.0.

       --cert-type <type>
              (TLS) Tells curl what type the provided client certificate
              is using. PEM, DER, ENG and P12 are recognized types.  If
              not specified, PEM is assumed.

              If this option is used several times, the last one will be
              used.

              See also -E, --cert, --key and --key-type.

       -E, --cert <certificate[:password]>
              (TLS) Tells curl to use the specified client certificate
              file when getting a file with HTTPS, FTPS or another SSL-
              based protocol. The certificate must be in PKCS#12 format
              if using Secure Transport, or PEM format if using any
              other engine.  If the optional password isn't specified,
              it will be queried for on the terminal. Note that this
              option assumes a "certificate" file that is the private
              key and the client certificate concatenated! See -E,
              --cert and --key to specify them independently.

              If curl is built against the NSS SSL library then this
              option can tell curl the nickname of the certificate to
              use within the NSS database defined by the environment
              variable SSL_DIR (or by default /etc/pki/nssdb). If the
              NSS PEM PKCS#11 module (libnsspem.so) is available then
              PEM files may be loaded. If you want to use a file from
              the current directory, please precede it with "./" prefix,
              in order to avoid confusion with a nickname.  If the
              nickname contains ":", it needs to be preceded by "\" so
              that it is not recognized as password delimiter.  If the
              nickname contains "\", it needs to be escaped as "\\" so
              that it is not recognized as an escape character.

              If curl is built against OpenSSL library, and the engine
              pkcs11 is available, then a PKCS#11 URI (RFC 7512) can be
              used to specify a certificate located in a PKCS#11 device.
              A string beginning with "pkcs11:" will be interpreted as a
              PKCS#11 URI. If a PKCS#11 URI is provided, then the
              --engine option will be set as "pkcs11" if none was
              provided and the --cert-type option will be set as "ENG"
              if none was provided.

              (iOS and macOS only) If curl is built against Secure
              Transport, then the certificate string can either be the
              name of a certificate/private key in the system or user
              keychain, or the path to a PKCS#12-encoded certificate and
              private key. If you want to use a file from the current
              directory, please precede it with "./" prefix, in order to
              avoid confusion with a nickname.

              (Schannel only) Client certificates must be specified by a
              path expression to a certificate store. (Loading PFX is
              not supported; you can import it to a store first). You
              can use "<store location>\<store name>\<thumbprint>" to
              refer to a certificate in the system certificates store,
              for example,
              "CurrentUser\MY\934a7ac6f8a5d579285a74fa61e19f23ddfe8d7a".
              Thumbprint is usually a SHA-1 hex string which you can see
              in certificate details. Following store locations are
              supported: CurrentUser, LocalMachine, CurrentService,
              Services, CurrentUserGroupPolicy, LocalMachineGroupPolicy,
              LocalMachineEnterprise.

              If this option is used several times, the last one will be
              used.

              See also --cert-type, --key and --key-type.

       --ciphers <list of ciphers>
              (TLS) Specifies which ciphers to use in the connection.
              The list of ciphers must specify valid ciphers. Read up on
              SSL cipher list details on this URL:

               https://curl.se/docs/ssl-ciphers.html

              If this option is used several times, the last one will be
              used.

       --compressed-ssh
              (SCP SFTP) Enables built-in SSH compression.  This is a
              request, not an order; the server may or may not do it.

              Added in 7.56.0.

       --compressed
              (HTTP) Request a compressed response using one of the
              algorithms curl supports, and automatically decompress the
              content. Headers are not modified.

              If this option is used and the server sends an unsupported
              encoding, curl will report an error.

       -K, --config <file>

              Specify a text file to read curl arguments from. The
              command line arguments found in the text file will be used
              as if they were provided on the command line.

              Options and their parameters must be specified on the same
              line in the file, separated by whitespace, colon, or the
              equals sign. Long option names can optionally be given in
              the config file without the initial double dashes and if
              so, the colon or equals characters can be used as
              separators. If the option is specified with one or two
              dashes, there can be no colon or equals character between
              the option and its parameter.

              If the parameter contains whitespace (or starts with : or
              =), the parameter must be enclosed within quotes. Within
              double quotes, the following escape sequences are
              available: \\, \", \t, \n, \r and \v. A backslash
              preceding any other letter is ignored. If the first column
              of a config line is a '#' character, the rest of the line
              will be treated as a comment. Only write one option per
              physical line in the config file.

              Specify the filename to -K, --config as '-' to make curl
              read the file from stdin.

              Note that to be able to specify a URL in the config file,
              you need to specify it using the --url option, and not by
              simply writing the URL on its own line. So, it could look
              similar to this:

              url = "https://curl.se/docs/"

              When curl is invoked, it (unless -q, --disable is used)
              checks for a default config file and uses it if found. The
              default config file is checked for in the following places
              in this order:

              1) Use the CURL_HOME environment variable if set

              2) Use the XDG_CONFIG_HOME environment variable if set
              (Added in 7.73.0)

              3) Use the HOME environment variable if set

              4) Non-windows: use getpwuid to find the home directory

              5) Windows: use APPDATA if set

              6) Windows: use "USERPROFILE0lication Data" if set

              7) On windows, if there is no .curlrc file in the home
              dir, it checks for one in the same dir the curl executable
              is placed. On Unix-like systems, it will simply try to
              load .curlrc from the determined home dir.

              # --- Example file ---
              # this is a comment
              url = "example.com"
              output = "curlhere.html"
              user-agent = "superagent/1.0"

              # and fetch another URL too
              url = "example.com/docs/manpage.html"
              -O
              referer = "http://nowhereatall.example.com/"
              # --- End of example file ---

              This option can be used multiple times to load multiple
              config files.

       --connect-timeout <seconds>
              Maximum time in seconds that you allow curl's connection
              to take.  This only limits the connection phase, so if
              curl connects within the given period it will continue -
              if not it will exit.  Since version 7.32.0, this option
              accepts decimal values.

              If this option is used several times, the last one will be
              used.

              See also -m, --max-time.

       --connect-to <HOST1:PORT1:HOST2:PORT2>

              For a request to the given HOST1:PORT1 pair, connect to
              HOST2:PORT2 instead.  This option is suitable to direct
              requests at a specific server, e.g. at a specific cluster
              node in a cluster of servers. This option is only used to
              establish the network connection. It does NOT affect the
              hostname/port that is used for TLS/SSL (e.g. SNI,
              certificate verification) or for the application
              protocols. "HOST1" and "PORT1" may be the empty string,
              meaning "any host/port". "HOST2" and "PORT2" may also be
              the empty string, meaning "use the request's original
              host/port".

              A "host" specified to this option is compared as a string,
              so it needs to match the name used in request URL. It can
              be either numerical such as "127.0.0.1" or the full host
              name such as "example.org".

              This option can be used many times to add many connect
              rules.

              See also --resolve and -H, --header. Added in 7.49.0.

       -C, --continue-at <offset>
              Continue/Resume a previous file transfer at the given
              offset. The given offset is the exact number of bytes that
              will be skipped, counting from the beginning of the source
              file before it is transferred to the destination.  If used
              with uploads, the FTP server command SIZE will not be used
              by curl.

              Use "-C -" to tell curl to automatically find out
              where/how to resume the transfer. It then uses the given
              output/input files to figure that out.

              If this option is used several times, the last one will be
              used.

              See also -r, --range.

       -c, --cookie-jar <filename>
              (HTTP) Specify to which file you want curl to write all
              cookies after a completed operation. Curl writes all
              cookies from its in-memory cookie storage to the given
              file at the end of operations. If no cookies are known, no
              data will be written. The file will be written using the
              Netscape cookie file format. If you set the file name to a
              single dash, "-", the cookies will be written to stdout.

              This command line option will activate the cookie engine
              that makes curl record and use cookies. Another way to
              activate it is to use the -b, --cookie option.

              If the cookie jar can't be created or written to, the
              whole curl operation won't fail or even report an error
              clearly. Using -v, --verbose will get a warning displayed,
              but that is the only visible feedback you get about this
              possibly lethal situation.

              If this option is used several times, the last specified
              file name will be used.

       -b, --cookie <data|filename>
              (HTTP) Pass the data to the HTTP server in the Cookie
              header. It is supposedly the data previously received from
              the server in a "Set-Cookie:" line.  The data should be in
              the format "NAME1=VALUE1; NAME2=VALUE2".

              If no '=' symbol is used in the argument, it is instead
              treated as a filename to read previously stored cookie
              from. This option also activates the cookie engine which
              will make curl record incoming cookies, which may be handy
              if you're using this in combination with the -L,
              --location option or do multiple URL transfers on the same
              invoke. If the file name is exactly a minus ("-"), curl
              will instead read the contents from stdin.

              The file format of the file to read cookies from should be
              plain HTTP headers (Set-Cookie style) or the
              Netscape/Mozilla cookie file format.

              The file specified with -b, --cookie is only used as
              input. No cookies will be written to the file. To store
              cookies, use the -c, --cookie-jar option.

              If you use the Set-Cookie file format and don't specify a
              domain then the cookie is not sent since the domain will
              never match. To address this, set a domain in Set-Cookie
              line (doing that will include sub-domains) or preferably:
              use the Netscape format.

              This option can be used multiple times.

              Users very often want to both read cookies from a file and
              write updated cookies back to a file, so using both -b,
              --cookie and -c, --cookie-jar in the same command line is
              common.

       --create-dirs
              When used in conjunction with the -o, --output option,
              curl will create the necessary local directory hierarchy
              as needed. This option creates the dirs mentioned with the
              -o, --output option, nothing else. If the --output file
              name uses no dir or if the dirs it mentions already exist,
              no dir will be created.

              Created dirs are made with mode 0750 on unix style file
              systems.

              To create remote directories when using FTP or SFTP, try
              --ftp-create-dirs.

       --create-file-mode <mode>
              (SFTP SCP FILE) When curl is used to create files remotely
              using one of the supported protocols, this option allows
              the user to set which 'mode' to set on the file at
              creation time, instead of the default 0644.

              This option takes an octal number as argument.

              See also --ftp-create-dirs. Added in 7.75.0.

       --crlf (FTP SMTP) Convert LF to CRLF in upload. Useful for MVS
              (OS/390).

              (SMTP added in 7.40.0)

       --crlfile <file>
              (TLS) Provide a file using PEM format with a Certificate
              Revocation List that may specify peer certificates that
              are to be considered revoked.

              If this option is used several times, the last one will be
              used.

              Added in 7.19.7.

       --curves <algorithm list>
              (TLS) Tells curl to request specific curves to use during
              SSL session establishment according to RFC 8422, 5.1.
              Multiple algorithms can be provided by separating them
              with ":" (e.g.  "X25519:P-521").  The parameter is
              available identically in the "openssl s_client/s_server"
              utilities.

              --curves allows a OpenSSL powered curl to make SSL-
              connections with exactly the (EC) curve requested by the
              client, avoiding intransparent client/server negotiations.

              If this option is set, the default curves list built into
              openssl will be ignored.

              Added in 7.73.0.

       --data-ascii <data>
              (HTTP) This is just an alias for -d, --data.

       --data-binary <data>
              (HTTP) This posts data exactly as specified with no extra
              processing whatsoever.

              If you start the data with the letter @, the rest should
              be a filename.  Data is posted in a similar manner as -d,
              --data does, except that newlines and carriage returns are
              preserved and conversions are never done.

              Like -d, --data the default content-type sent to the
              server is application/x-www-form-urlencoded. If you want
              the data to be treated as arbitrary binary data by the
              server then set the content-type to octet-stream: -H
              "Content-Type: application/octet-stream".

              If this option is used several times, the ones following
              the first will append data as described in -d, --data.

       --data-raw <data>
              (HTTP) This posts data similarly to -d, --data but without
              the special interpretation of the @ character.

              See also -d, --data. Added in 7.43.0.

       --data-urlencode <data>
              (HTTP) This posts data, similar to the other -d, --data
              options with the exception that this performs URL-
              encoding.

              To be CGI-compliant, the <data> part should begin with a
              name followed by a separator and a content specification.
              The <data> part can be passed to curl using one of the
              following syntaxes:

              content
                     This will make curl URL-encode the content and pass
                     that on. Just be careful so that the content
                     doesn't contain any = or @ symbols, as that will
                     then make the syntax match one of the other cases
                     below!

              =content
                     This will make curl URL-encode the content and pass
                     that on. The preceding = symbol is not included in
                     the data.

              name=content
                     This will make curl URL-encode the content part and
                     pass that on. Note that the name part is expected
                     to be URL-encoded already.

              @filename
                     This will make curl load data from the given file
                     (including any newlines), URL-encode that data and
                     pass it on in the POST.

              name@filename
                     This will make curl load data from the given file
                     (including any newlines), URL-encode that data and
                     pass it on in the POST. The name part gets an equal
                     sign appended, resulting in name=urlencoded-file-
                     content. Note that the name is expected to be URL-
                     encoded already.

       See also -d, --data and --data-raw. Added in 7.18.0.

       -d, --data <data>
              (HTTP MQTT) Sends the specified data in a POST request to
              the HTTP server, in the same way that a browser does when
              a user has filled in an HTML form and presses the submit
              button. This will cause curl to pass the data to the
              server using the content-type application/x-www-form-
              urlencoded.  Compare to -F, --form.

              --data-raw is almost the same but does not have a special
              interpretation of the @ character. To post data purely
              binary, you should instead use the --data-binary option.
              To URL-encode the value of a form field you may use
              --data-urlencode.

              If any of these options is used more than once on the same
              command line, the data pieces specified will be merged
              together with a separating &-symbol. Thus, using '-d
              name=daniel -d skill=lousy' would generate a post chunk
              that looks like 'name=daniel&skill=lousy'.

              If you start the data with the letter @, the rest should
              be a file name to read the data from, or - if you want
              curl to read the data from stdin. Posting data from a file
              named 'foobar' would thus be done with -d, --data @foobar.
              When -d, --data is told to read from a file like that,
              carriage returns and newlines will be stripped out. If you
              don't want the @ character to have a special
              interpretation use --data-raw instead.

              See also --data-binary, --data-urlencode and --data-raw.
              This option overrides -F, --form and -I, --head and -T,
              --upload-file.

       --delegation <LEVEL>
              (GSS/kerberos) Set LEVEL to tell the server what it is
              allowed to delegate when it comes to user credentials.

              none   Don't allow any delegation.

              policy Delegates if and only if the OK-AS-DELEGATE flag is
                     set in the Kerberos service ticket, which is a
                     matter of realm policy.

              always Unconditionally allow the server to delegate.

       --digest
              (HTTP) Enables HTTP Digest authentication. This is an
              authentication scheme that prevents the password from
              being sent over the wire in clear text. Use this in
              combination with the normal -u, --user option to set user
              name and password.

              If this option is used several times, only the first one
              is used.

              See also -u, --user, --proxy-digest and --anyauth. This
              option overrides --basic and --ntlm and --negotiate.

       --disable-eprt
              (FTP) Tell curl to disable the use of the EPRT and LPRT
              commands when doing active FTP transfers. Curl will
              normally always first attempt to use EPRT, then LPRT
              before using PORT, but with this option, it will use PORT
              right away. EPRT and LPRT are extensions to the original
              FTP protocol, and may not work on all servers, but they
              enable more functionality in a better way than the
              traditional PORT command.

              --eprt can be used to explicitly enable EPRT again and
              --no-eprt is an alias for --disable-eprt.

              If the server is accessed using IPv6, this option will
              have no effect as EPRT is necessary then.

              Disabling EPRT only changes the active behavior. If you
              want to switch to passive mode you need to not use -P,
              --ftp-port or force it with --ftp-pasv.

       --disable-epsv
              (FTP) (FTP) Tell curl to disable the use of the EPSV
              command when doing passive FTP transfers. Curl will
              normally always first attempt to use EPSV before PASV, but
              with this option, it will not try using EPSV.

              --epsv can be used to explicitly enable EPSV again and
              --no-epsv is an alias for --disable-epsv.

              If the server is an IPv6 host, this option will have no
              effect as EPSV is necessary then.

              Disabling EPSV only changes the passive behavior. If you
              want to switch to active mode you need to use -P, --ftp-
              port.

       -q, --disable
              If used as the first parameter on the command line, the
              curlrc config file will not be read and used. See the -K,
              --config for details on the default config file search
              path.

       --disallow-username-in-url
              (HTTP) This tells curl to exit if passed a url containing
              a username.

              See also --proto. Added in 7.61.0.

       --dns-interface <interface>
              (DNS) Tell curl to send outgoing DNS requests through
              <interface>. This option is a counterpart to --interface
              (which does not affect DNS). The supplied string must be
              an interface name (not an address).

              See also --dns-ipv4-addr and --dns-ipv6-addr. --dns-
              interface requires that the underlying libcurl was built
              to support c-ares. Added in 7.33.0.

       --dns-ipv4-addr <address>
              (DNS) Tell curl to bind to <ip-address> when making IPv4
              DNS requests, so that the DNS requests originate from this
              address. The argument should be a single IPv4 address.

              See also --dns-interface and --dns-ipv6-addr. --dns-
              ipv4-addr requires that the underlying libcurl was built
              to support c-ares. Added in 7.33.0.

       --dns-ipv6-addr <address>
              (DNS) Tell curl to bind to <ip-address> when making IPv6
              DNS requests, so that the DNS requests originate from this
              address. The argument should be a single IPv6 address.

              See also --dns-interface and --dns-ipv4-addr. --dns-
              ipv6-addr requires that the underlying libcurl was built
              to support c-ares. Added in 7.33.0.

       --dns-servers <addresses>
              Set the list of DNS servers to be used instead of the
              system default.  The list of IP addresses should be
              separated with commas. Port numbers may also optionally be
              given as :<port-number> after each IP address.

              --dns-servers requires that the underlying libcurl was
              built to support c-ares. Added in 7.33.0.

       --doh-cert-status
              (all) Same as --cert-status but used for DOH (DNS-over-
              HTTPS).

              Added in 7.76.0.

       --doh-insecure
              (all) Same as -k, --insecure but used for DOH (DNS-over-
              HTTPS).

              Added in 7.76.0.

       --doh-url <URL>
              (all) Specifies which DNS-over-HTTPS (DOH) server to use
              to resolve hostnames, instead of using the default name
              resolver mechanism. The URL must be HTTPS.

              Some SSL options that you set for your transfer will apply
              to DOH since the name lookups take place over SSL.
              However, the certificate verification settings are not
              inherited and can be controlled separately via --doh-
              insecure and --doh-cert-status.

              If this option is used several times, the last one will be
              used.

              Added in 7.62.0.

       -D, --dump-header <filename>
              (HTTP FTP) Write the received protocol headers to the
              specified file.

              This option is handy to use when you want to store the
              headers that an HTTP site sends to you. Cookies from the
              headers could then be read in a second curl invocation by
              using the -b, --cookie option! The -c, --cookie-jar option
              is a better way to store cookies.

              If no headers are received, the use of this option will
              create an empty file.

              When used in FTP, the FTP server response lines are
              considered being "headers" and thus are saved there.

              If this option is used several times, the last one will be
              used.

              See also -o, --output.

       --egd-file <file>
              (TLS) Specify the path name to the Entropy Gathering
              Daemon socket. The socket is used to seed the random
              engine for SSL connections.

              See also --random-file.

       --engine <name>
              (TLS) Select the OpenSSL crypto engine to use for cipher
              operations. Use --engine list to print a list of build-
              time supported engines. Note that not all (or none) of the
              engines may be available at run-time.

       --etag-compare <file>
              (HTTP) This option makes a conditional HTTP request for
              the specific ETag read from the given file by sending a
              custom If-None-Match header using the extracted ETag.

              For correct results, make sure that specified file
              contains only a single line with a desired ETag. An empty
              file is parsed as an empty ETag.

              Use the option --etag-save to first save the ETag from a
              response, and then use this option to compare using the
              saved ETag in a subsequent request.

              COMPARISON: There are 2 types of comparison or ETags: Weak
              and Strong.  This option expects, and uses a strong
              comparison.

              Added in 7.68.0.

       --etag-save <file>
              (HTTP) This option saves an HTTP ETag to the specified
              file. Etag is usually part of headers returned by a
              request. When server sends an ETag, it must be enveloped
              by a double quote. This option extracts the ETag without
              the double quotes and saves it into the <file>.

              A server can send a weak ETag which is prefixed by "W/".
              This identifier is not considered, and only relevant ETag
              between quotation marks is parsed.

              It an ETag wasn't sent by the server or it cannot be
              parsed, an empty file is created.

              Added in 7.68.0.

       --expect100-timeout <seconds>
              (HTTP) Maximum time in seconds that you allow curl to wait
              for a 100-continue response when curl emits an Expects:
              100-continue header in its request. By default curl will
              wait one second. This option accepts decimal values! When
              curl stops waiting, it will continue as if the response
              has been received.

              See also --connect-timeout. Added in 7.47.0.

       --fail-early
              Fail and exit on the first detected transfer error.

              When curl is used to do multiple transfers on the command
              line, it will attempt to operate on each given URL, one by
              one. By default, it will ignore errors if there are more
              URLs given and the last URL's success will determine the
              error code curl returns. So early failures will be
              "hidden" by subsequent successful transfers.

              Using this option, curl will instead return an error on
              the first transfer that fails, independent of the amount
              of URLs that are given on the command line. This way, no
              transfer failures go undetected by scripts and similar.

              This option is global and does not need to be specified
              for each use of -:, --next.

              This option does not imply -f, --fail, which causes
              transfers to fail due to the server's HTTP status code.
              You can combine the two options, however note -f, --fail
              is not global and is therefore contained by -:, --next.

              Added in 7.52.0.

       --fail-with-body
              (HTTP) Return an error on server errors where the HTTP
              response code is 400 or greater). In normal cases when an
              HTTP server fails to deliver a document, it returns an
              HTML document stating so (which often also describes why
              and more). This flag will still allow curl to output and
              save that content but also to return error 22.

              This is an alternative option to -f, --fail which makes
              curl fail for the same circumstances but without saving
              the content.

              See also -f, --fail. Added in 7.76.0.

       -f, --fail
              (HTTP) Fail silently (no output at all) on server errors.
              This is mostly done to enable scripts etc to better deal
              with failed attempts. In normal cases when an HTTP server
              fails to deliver a document, it returns an HTML document
              stating so (which often also describes why and more). This
              flag will prevent curl from outputting that and return
              error 22.

              This method is not fail-safe and there are occasions where
              non-successful response codes will slip through,
              especially when authentication is involved (response codes
              401 and 407).

              See also --fail-with-body.

       --false-start
              (TLS) Tells curl to use false start during the TLS
              handshake. False start is a mode where a TLS client will
              start sending application data before verifying the
              server's Finished message, thus saving a round trip when
              performing a full handshake.

              This is currently only implemented in the NSS and Secure
              Transport (on iOS 7.0 or later, or OS X 10.9 or later)
              backends.

              Added in 7.42.0.

       --form-string <name=string>
              (HTTP SMTP IMAP) Similar to -F, --form except that the
              value string for the named parameter is used literally.
              Leading '@' and '<' characters, and the ';type=' string in
              the value have no special meaning. Use this in preference
              to -F, --form if there's any possibility that the string
              value may accidentally trigger the '@' or '<' features of
              -F, --form.

              See also -F, --form.

       -F, --form <name=content>
              (HTTP SMTP IMAP) For HTTP protocol family, this lets curl
              emulate a filled-in form in which a user has pressed the
              submit button. This causes curl to POST data using the
              Content-Type multipart/form-data according to RFC 2388.

              For SMTP and IMAP protocols, this is the mean to compose a
              multipart mail message to transmit.

              This enables uploading of binary files etc. To force the
              'content' part to be a file, prefix the file name with an
              @ sign. To just get the content part from a file, prefix
              the file name with the symbol <. The difference between @
              and < is then that @ makes a file get attached in the post
              as a file upload, while the < makes a text field and just
              get the contents for that text field from a file.

              Tell curl to read content from stdin instead of a file by
              using - as filename. This goes for both @ and <
              constructs. When stdin is used, the contents is buffered
              in memory first by curl to determine its size and allow a
              possible resend.  Defining a part's data from a named non-
              regular file (such as a named pipe or similar) is
              unfortunately not subject to buffering and will be
              effectively read at transmission time; since the full size
              is unknown before the transfer starts, such data is sent
              as chunks by HTTP and rejected by IMAP.

              Example: send an image to an HTTP server, where 'profile'
              is the name of the form-field to which the file
              portrait.jpg will be the input:

               curl -F profile=@portrait.jpg
              https://example.com/upload.cgi

              Example: send your name and shoe size in two text fields
              to the server:

               curl -F name=John -F shoesize=11 https://example.com/

              Example: send your essay in a text field to the server.
              Send it as a plain text field, but get the contents for it
              from a local file:

               curl -F "story=<hugefile.txt" https://example.com/

              You can also tell curl what Content-Type to use by using
              'type=', in a manner similar to:

               curl -F "web=@index.html;type=text/html" example.com

              or

               curl -F "name=daniel;type=text/foo" example.com

              You can also explicitly change the name field of a file
              upload part by setting filename=, like this:

               curl -F "file=@localfile;filename=nameinpost" example.com

              If filename/path contains ',' or ';', it must be quoted by
              double-quotes like:

               curl -F "file=@\"localfile\";filename=\"nameinpost\""
              example.com

              or

               curl -F 'file=@"localfile";filename="nameinpost"'
              example.com

              Note that if a filename/path is quoted by double-quotes,
              any double-quote or backslash within the filename must be
              escaped by backslash.

              Quoting must also be applied to non-file data if it
              contains semicolons, leading/trailing spaces or leading
              double quotes:

               curl -F 'colors="red; green; blue";type=text/x-myapp'
              example.com

              You can add custom headers to the field by setting
              headers=, like

                curl -F "submit=OK;headers=\"X-submit-type: OK\""
              example.com

              or

                curl -F "submit=OK;headers=@headerfile" example.com

              The headers= keyword may appear more that once and above
              notes about quoting apply. When headers are read from a
              file, Empty lines and lines starting with '#' are comments
              and ignored; each header can be folded by splitting
              between two words and starting the continuation line with
              a space; embedded carriage-returns and trailing spaces are
              stripped.  Here is an example of a header file contents:

                # This file contain two headers.
                X-header-1: this is a header

                # The following header is folded.
                X-header-2: this is
                 another header

              To support sending multipart mail messages, the syntax is
              extended as follows:
              - name can be omitted: the equal sign is the first
              character of the argument,
              - if data starts with '(', this signals to start a new
              multipart: it can be followed by a content type
              specification.
              - a multipart can be terminated with a '=)' argument.

              Example: the following command sends an SMTP mime e-mail
              consisting in an inline part in two alternative formats:
              plain text and HTML. It attaches a text file:

               curl -F '=(;type=multipart/alternative' \
                       -F '=plain text message' \
                       -F '= <body>HTML message</body>;type=text/html' \
                    -F '=)' -F '=@textfile.txt' ...  smtp://example.com

              Data can be encoded for transfer using encoder=. Available
              encodings are binary and 8bit that do nothing else than
              adding the corresponding Content-Transfer-Encoding header,
              7bit that only rejects 8-bit characters with a transfer
              error, quoted-printable and base64 that encodes data
              according to the corresponding schemes, limiting lines
              length to 76 characters.

              Example: send multipart mail with a quoted-printable text
              message and a base64 attached file:

               curl -F '=text message;encoder=quoted-printable' \
                    -F '=@localfile;encoder=base64' ...
              smtp://example.com

              See further examples and details in the MANUAL.

              This option can be used multiple times.

              This option overrides -d, --data and -I, --head and -T,
              --upload-file.

       --ftp-account <data>
              (FTP) When an FTP server asks for "account data" after
              user name and password has been provided, this data is
              sent off using the ACCT command.

              If this option is used several times, the last one will be
              used.

              Added in 7.13.0.

       --ftp-alternative-to-user <command>
              (FTP) If authenticating with the USER and PASS commands
              fails, send this command.  When connecting to Tumbleweed's
              Secure Transport server over FTPS using a client
              certificate, using "SITE AUTH" will tell the server to
              retrieve the username from the certificate.

              Added in 7.15.5.

       --ftp-create-dirs
              (FTP SFTP) When an FTP or SFTP URL/operation uses a path
              that doesn't currently exist on the server, the standard
              behavior of curl is to fail. Using this option, curl will
              instead attempt to create missing directories.

              See also --create-dirs.

       --ftp-method <method>
              (FTP) Control what method curl should use to reach a file
              on an FTP(S) server. The method argument should be one of
              the following alternatives:

              multicwd
                     curl does a single CWD operation for each path part
                     in the given URL. For deep hierarchies this means
                     very many commands. This is how RFC 1738 says it
                     should be done. This is the default but the slowest
                     behavior.

              nocwd  curl does no CWD at all. curl will do SIZE, RETR,
                     STOR etc and give a full path to the server for all
                     these commands. This is the fastest behavior.

              singlecwd
                     curl does one CWD with the full target directory
                     and then operates on the file "normally" (like in
                     the multicwd case). This is somewhat more standards
                     compliant than 'nocwd' but without the full penalty
                     of 'multicwd'.

       Added in 7.15.1.

       --ftp-pasv
              (FTP) Use passive mode for the data connection. Passive is
              the internal default behavior, but using this option can
              be used to override a previous -P, --ftp-port option.

              If this option is used several times, only the first one
              is used. Undoing an enforced passive really isn't doable
              but you must then instead enforce the correct -P, --ftp-
              port again.

              Passive mode means that curl will try the EPSV command
              first and then PASV, unless --disable-epsv is used.

              See also --disable-epsv. Added in 7.11.0.

       -P, --ftp-port <address>
              (FTP) Reverses the default initiator/listener roles when
              connecting with FTP. This option makes curl use active
              mode. curl then tells the server to connect back to the
              client's specified address and port, while passive mode
              asks the server to setup an IP address and port for it to
              connect to. <address> should be one of:

              interface
                     e.g. "eth0" to specify which interface's IP address
                     you want to use (Unix only)

              IP address
                     e.g. "192.168.10.1" to specify the exact IP address

              host name
                     e.g. "my.host.domain" to specify the machine

              -      make curl pick the same IP address that is already
                     used for the control connection

       If this option is used several times, the last one will be used.
       Disable the use of PORT with --ftp-pasv. Disable the attempt to
       use the EPRT command instead of PORT by using --disable-eprt.
       EPRT is really PORT++.

       Since 7.19.5, you can append ":[start]-[end]" to the right of the
       address, to tell curl what TCP port range to use. That means you
       specify a port range, from a lower to a higher number. A single
       number works as well, but do note that it increases the risk of
       failure since the port may not be available.

       See also --ftp-pasv and --disable-eprt.

       --ftp-pret
              (FTP) Tell curl to send a PRET command before PASV (and
              EPSV). Certain FTP servers, mainly drftpd, require this
              non-standard command for directory listings as well as up
              and downloads in PASV mode.

              Added in 7.20.0.

       --ftp-skip-pasv-ip
              (FTP) Tell curl to not use the IP address the server
              suggests in its response to curl's PASV command when curl
              connects the data connection. Instead curl will re-use the
              same IP address it already uses for the control
              connection.

              Since curl 7.74.0 this option is enabled by default.

              This option has no effect if PORT, EPRT or EPSV is used
              instead of PASV.

              See also --ftp-pasv. Added in 7.14.2.

       --ftp-ssl-ccc-mode <active/passive>
              (FTP) Sets the CCC mode. The passive mode will not
              initiate the shutdown, but instead wait for the server to
              do it, and will not reply to the shutdown from the server.
              The active mode initiates the shutdown and waits for a
              reply from the server.

              See also --ftp-ssl-ccc. Added in 7.16.2.

       --ftp-ssl-ccc
              (FTP) Use CCC (Clear Command Channel) Shuts down the
              SSL/TLS layer after authenticating. The rest of the
              control channel communication will be unencrypted. This
              allows NAT routers to follow the FTP transaction. The
              default mode is passive.

              See also --ssl and --ftp-ssl-ccc-mode. Added in 7.16.1.

       --ftp-ssl-control
              (FTP) Require SSL/TLS for the FTP login, clear for
              transfer.  Allows secure authentication, but non-encrypted
              data transfers for efficiency.  Fails the transfer if the
              server doesn't support SSL/TLS.

              Added in 7.16.0.

       -G, --get
              When used, this option will make all data specified with
              -d, --data, --data-binary or --data-urlencode to be used
              in an HTTP GET request instead of the POST request that
              otherwise would be used. The data will be appended to the
              URL with a '?' separator.

              If used in combination with -I, --head, the POST data will
              instead be appended to the URL with a HEAD request.

              If this option is used several times, only the first one
              is used. This is because undoing a GET doesn't make sense,
              but you should then instead enforce the alternative method
              you prefer.

       -g, --globoff
              This option switches off the "URL globbing parser". When
              you set this option, you can specify URLs that contain the
              letters {}[] without having them being interpreted by curl
              itself. Note that these letters are not normal legal URL
              contents but they should be encoded according to the URI
              standard.

       --happy-eyeballs-timeout-ms <milliseconds>
              Happy eyeballs is an algorithm that attempts to connect to
              both IPv4 and IPv6 addresses for dual-stack hosts,
              preferring IPv6 first for the number of milliseconds. If
              the IPv6 address cannot be connected to within that time
              then a connection attempt is made to the IPv4 address in
              parallel. The first connection to be established is the
              one that is used.

              The range of suggested useful values is limited. Happy
              Eyeballs RFC 6555 says "It is RECOMMENDED that connection
              attempts be paced 150-250 ms apart to balance human
              factors against network load." libcurl currently defaults
              to 200 ms. Firefox and Chrome currently default to 300 ms.

              If this option is used several times, the last one will be
              used.

              Added in 7.59.0.

       --haproxy-protocol
              (HTTP) Send a HAProxy PROXY protocol v1 header at the
              beginning of the connection. This is used by some load
              balancers and reverse proxies to indicate the client's
              true IP address and port.

              This option is primarily useful when sending test requests
              to a service that expects this header.

              Added in 7.60.0.

       -I, --head
              (HTTP FTP FILE) Fetch the headers only! HTTP-servers
              feature the command HEAD which this uses to get nothing
              but the header of a document. When used on an FTP or FILE
              file, curl displays the file size and last modification
              time only.

       -H, --header <header/@file>
              (HTTP) Extra header to include in the request when sending
              HTTP to a server. You may specify any number of extra
              headers. Note that if you should add a custom header that
              has the same name as one of the internal ones curl would
              use, your externally set header will be used instead of
              the internal one. This allows you to make even trickier
              stuff than curl would normally do. You should not replace
              internally set headers without knowing perfectly well what
              you're doing. Remove an internal header by giving a
              replacement without content on the right side of the
              colon, as in: -H "Host:". If you send the custom header
              with no-value then its header must be terminated with a
              semicolon, such as -H "X-Custom-Header;" to send "X-
              Custom-Header:".

              curl will make sure that each header you add/replace is
              sent with the proper end-of-line marker, you should thus
              not add that as a part of the header content: do not add
              newlines or carriage returns, they will only mess things
              up for you.

              This option can take an argument in @filename style, which
              then adds a header for each line in the input file. Using
              @- will make curl read the header file from stdin. Added
              in 7.55.0.

              You need --proxy-header to send custom headers intended
              for a HTTP proxy. Added in 7.37.0.

              Passing on a "Transfer-Encoding: chunked" header when
              doing a HTTP request with a request body, will make curl
              send the data using chunked encoding.

              Example:

               curl -H "X-First-Name: Joe" http://example.com/

              WARNING: headers set with this option will be set in all
              requests - even after redirects are followed, like when
              told with -L, --location. This can lead to the header
              being sent to other hosts than the original host, so
              sensitive headers should be used with caution combined
              with following redirects.

              This option can be used multiple times to
              add/replace/remove multiple headers.

              See also -A, --user-agent and -e, --referer.

       -h, --help <category>
              Usage help. This lists all commands of the <category>.  If
              no arg was provided, curl will display the most important
              command line arguments.  If the argument "all" was
              provided, curl will display all options available.  If the
              argument "category" was provided, curl will display all
              categories and their meanings.

       --hostpubmd5 <md5>
              (SFTP SCP) Pass a string containing 32 hexadecimal digits.
              The string should be the 128 bit MD5 checksum of the
              remote host's public key, curl will refuse the connection
              with the host unless the md5sums match.

              Added in 7.17.1.

       --hsts <file name>
              (HTTPS) WARNING: this option is experimental. Do not use
              in production.

              This option enables HSTS for the transfer. If the file
              name points to an existing HSTS cache file, that will be
              used. After a completed transfer, the cache will be saved
              to the file name again if it has been modified.

              Specify a "" file name (zero length) to avoid
              loading/saving and make curl just handle HSTS in memory.

              If this option is used several times, curl will load
              contents from all the files but the last one will be used
              for saving.

              Added in 7.74.0.

       --http0.9
              (HTTP) Tells curl to be fine with HTTP version 0.9
              response.

              HTTP/0.9 is a completely headerless response and therefore
              you can also connect with this to non-HTTP servers and
              still get a response since curl will simply transparently
              downgrade - if allowed.

              Since curl 7.66.0, HTTP/0.9 is disabled by default.

       -0, --http1.0
              (HTTP) Tells curl to use HTTP version 1.0 instead of using
              its internally preferred HTTP version.

              This option overrides --http1.1 and --http2.

       --http1.1
              (HTTP) Tells curl to use HTTP version 1.1.

              This option overrides -0, --http1.0 and --http2. Added in
              7.33.0.

       --http2-prior-knowledge
              (HTTP) Tells curl to issue its non-TLS HTTP requests using
              HTTP/2 without HTTP/1.1 Upgrade. It requires prior
              knowledge that the server supports HTTP/2 straight away.
              HTTPS requests will still do HTTP/2 the standard way with
              negotiated protocol version in the TLS handshake.

              --http2-prior-knowledge requires that the underlying
              libcurl was built to support HTTP/2. This option overrides
              --http1.1 and -0, --http1.0 and --http2. Added in 7.49.0.

       --http2
              (HTTP) Tells curl to use HTTP version 2.

              See also --http1.1 and --http3. --http2 requires that the
              underlying libcurl was built to support HTTP/2. This
              option overrides --http1.1 and -0, --http1.0 and
              --http2-prior-knowledge. Added in 7.33.0.

       --http3
              (HTTP) WARNING: this option is experimental. Do not use in
              production.

              Tells curl to use HTTP version 3 directly to the host and
              port number used in the URL. A normal HTTP/3 transaction
              will be done to a host and then get redirected via Alt-
              SVc, but this option allows a user to circumvent that when
              you know that the target speaks HTTP/3 on the given host
              and port.

              This option will make curl fail if a QUIC connection
              cannot be established, it cannot fall back to a lower HTTP
              version on its own.

              See also --http1.1 and --http2. --http3 requires that the
              underlying libcurl was built to support HTTP/3. This
              option overrides --http1.1 and -0, --http1.0 and --http2
              and --http2-prior-knowledge. Added in 7.66.0.

       --ignore-content-length
              (FTP HTTP) For HTTP, Ignore the Content-Length header.
              This is particularly useful for servers running Apache
              1.x, which will report incorrect Content-Length for files
              larger than 2 gigabytes.

              For FTP (since 7.46.0), skip the RETR command to figure
              out the size before downloading a file.

              This option doesn't work if libcurl was built to use hyper
              for HTTP.

       -i, --include
              Include the HTTP response headers in the output. The HTTP
              response headers can include things like server name,
              cookies, date of the document, HTTP version and more...

              To view the request headers, consider the -v, --verbose
              option.

              See also -v, --verbose.

       -k, --insecure
              (TLS) By default, every SSL connection curl makes is
              verified to be secure. This option allows curl to proceed
              and operate even for server connections otherwise
              considered insecure.

              The server connection is verified by making sure the
              server's certificate contains the right name and verifies
              successfully using the cert store.

              See this online resource for further details:
               https://curl.se/docs/sslcerts.html

              See also --proxy-insecure and --cacert.

       --interface <name>

              Perform an operation using a specified interface. You can
              enter interface name, IP address or host name. An example
              could look like:

               curl --interface eth0:1 https://www.example.com/

              If this option is used several times, the last one will be
              used.

              On Linux it can be used to specify a VRF, but the binary
              needs to either have CAP_NET_RAW or to be run as root.
              More information about Linux VRF:
              https://www.kernel.org/doc/Documentation/networking/vrf.txt

              See also --dns-interface.

       -4, --ipv4
              This option tells curl to resolve names to IPv4 addresses
              only, and not for example try IPv6.

              See also --http1.1 and --http2. This option overrides -6,
              --ipv6.

       -6, --ipv6
              This option tells curl to resolve names to IPv6 addresses
              only, and not for example try IPv4.

              See also --http1.1 and --http2. This option overrides -4,
              --ipv4.

       -j, --junk-session-cookies
              (HTTP) When curl is told to read cookies from a given
              file, this option will make it discard all "session
              cookies". This will basically have the same effect as if a
              new session is started. Typical browsers always discard
              session cookies when they're closed down.

              See also -b, --cookie and -c, --cookie-jar.

       --keepalive-time <seconds>
              This option sets the time a connection needs to remain
              idle before sending keepalive probes and the time between
              individual keepalive probes. It is currently effective on
              operating systems offering the TCP_KEEPIDLE and
              TCP_KEEPINTVL socket options (meaning Linux, recent AIX,
              HP-UX and more). This option has no effect if --no-
              keepalive is used.

              If this option is used several times, the last one will be
              used. If unspecified, the option defaults to 60 seconds.

              Added in 7.18.0.

       --key-type <type>
              (TLS) Private key file type. Specify which type your --key
              provided private key is. DER, PEM, and ENG are supported.
              If not specified, PEM is assumed.

              If this option is used several times, the last one will be
              used.

       --key <key>
              (TLS SSH) Private key file name. Allows you to provide
              your private key in this separate file. For SSH, if not
              specified, curl tries the following candidates in order:
              '~/.ssh/id_rsa', '~/.ssh/id_dsa', './id_rsa', './id_dsa'.

              If curl is built against OpenSSL library, and the engine
              pkcs11 is available, then a PKCS#11 URI (RFC 7512) can be
              used to specify a private key located in a PKCS#11 device.
              A string beginning with "pkcs11:" will be interpreted as a
              PKCS#11 URI. If a PKCS#11 URI is provided, then the
              --engine option will be set as "pkcs11" if none was
              provided and the --key-type option will be set as "ENG" if
              none was provided.

              If this option is used several times, the last one will be
              used.

       --krb <level>
              (FTP) Enable Kerberos authentication and use. The level
              must be entered and should be one of 'clear', 'safe',
              'confidential', or 'private'. Should you use a level that
              is not one of these, 'private' will instead be used.

              If this option is used several times, the last one will be
              used.

              --krb requires that the underlying libcurl was built to
              support Kerberos.

       --libcurl <file>
              Append this option to any ordinary curl command line, and
              you will get a libcurl-using C source code written to the
              file that does the equivalent of what your command-line
              operation does!

              If this option is used several times, the last given file
              name will be used.

              Added in 7.16.1.

       --limit-rate <speed>
              Specify the maximum transfer rate you want curl to use -
              for both downloads and uploads. This feature is useful if
              you have a limited pipe and you'd like your transfer not
              to use your entire bandwidth. To make it slower than it
              otherwise would be.

              The given speed is measured in bytes/second, unless a
              suffix is appended.  Appending 'k' or 'K' will count the
              number as kilobytes, 'm' or 'M' makes it megabytes, while
              'g' or 'G' makes it gigabytes. Examples: 200K, 3m and 1G.

              If you also use the -Y, --speed-limit option, that option
              will take precedence and might cripple the rate-limiting
              slightly, to help keeping the speed-limit logic working.

              If this option is used several times, the last one will be
              used.

       -l, --list-only
              (FTP POP3) (FTP) When listing an FTP directory, this
              switch forces a name-only view. This is especially useful
              if the user wants to machine-parse the contents of an FTP
              directory since the normal directory view doesn't use a
              standard look or format. When used like this, the option
              causes a NLST command to be sent to the server instead of
              LIST.

              Note: Some FTP servers list only files in their response
              to NLST; they do not include sub-directories and symbolic
              links.

              (POP3) When retrieving a specific email from POP3, this
              switch forces a LIST command to be performed instead of
              RETR. This is particularly useful if the user wants to see
              if a specific message id exists on the server and what
              size it is.

              Note: When combined with -X, --request, this option can be
              used to send an UIDL command instead, so the user may use
              the email's unique identifier rather than it's message id
              to make the request.

              Added in 4.0.

       --local-port <num/range>
              Set a preferred single number or range (FROM-TO) of local
              port numbers to use for the connection(s).  Note that port
              numbers by nature are a scarce resource that will be busy
              at times so setting this range to something too narrow
              might cause unnecessary connection setup failures.

              Added in 7.15.2.

       --location-trusted
              (HTTP) Like -L, --location, but will allow sending the
              name + password to all hosts that the site may redirect
              to. This may or may not introduce a security breach if the
              site redirects you to a site to which you'll send your
              authentication info (which is plaintext in the case of
              HTTP Basic authentication).

              See also -u, --user.

       -L, --location
              (HTTP) If the server reports that the requested page has
              moved to a different location (indicated with a Location:
              header and a 3XX response code), this option will make
              curl redo the request on the new place. If used together
              with -i, --include or -I, --head, headers from all
              requested pages will be shown. When authentication is
              used, curl only sends its credentials to the initial host.
              If a redirect takes curl to a different host, it won't be
              able to intercept the user+password. See also --location-
              trusted on how to change this. You can limit the amount of
              redirects to follow by using the --max-redirs option.

              When curl follows a redirect and if the request is a POST,
              it will do the following request with a GET if the HTTP
              response was 301, 302, or 303. If the response code was
              any other 3xx code, curl will re-send the following
              request using the same unmodified method.

              You can tell curl to not change POST requests to GET after
              a 30x response by using the dedicated options for that:
              --post301, --post302 and --post303.

              The method set with -X, --request overrides the method
              curl would otherwise select to use.

       --login-options <options>
              (IMAP POP3 SMTP) Specify the login options to use during
              server authentication.

              You can use the login options to specify protocol specific
              options that may be used during authentication. At present
              only IMAP, POP3 and SMTP support login options. For more
              information about the login options please see RFC 2384,
              RFC 5092 and IETF draft draft-earhart-url-smtp-00.txt

              If this option is used several times, the last one will be
              used.

              Added in 7.34.0.

       --mail-auth <address>
              (SMTP) Specify a single address. This will be used to
              specify the authentication address (identity) of a
              submitted message that is being relayed to another server.

              See also --mail-rcpt and --mail-from. Added in 7.25.0.

       --mail-from <address>
              (SMTP) Specify a single address that the given mail should
              get sent from.

              See also --mail-rcpt and --mail-auth. Added in 7.20.0.

       --mail-rcpt-allowfails
              (SMTP) When sending data to multiple recipients, by
              default curl will abort SMTP conversation if at least one
              of the recipients causes RCPT TO command to return an
              error.

              The default behavior can be changed by passing --mail-
              rcpt-allowfails command-line option which will make curl
              ignore errors and proceed with the remaining valid
              recipients.

              In case when all recipients cause RCPT TO command to fail,
              curl will abort SMTP conversation and return the error
              received from to the last RCPT TO command.  Added in
              7.69.0.

       --mail-rcpt <address>
              (SMTP) Specify a single address, user name or mailing list
              name. Repeat this option several times to send to multiple
              recipients.

              When performing a mail transfer, the recipient should
              specify a valid email address to send the mail to.

              When performing an address verification (VRFY command),
              the recipient should be specified as the user name or user
              name and domain (as per Section 3.5 of RFC5321). (Added in
              7.34.0)

              When performing a mailing list expand (EXPN command), the
              recipient should be specified using the mailing list name,
              such as "Friends" or "London-Office".  (Added in 7.34.0)

              Added in 7.20.0.

       -M, --manual
              Manual. Display the huge help text.

       --max-filesize <bytes>
              Specify the maximum size (in bytes) of a file to download.
              If the file requested is larger than this value, the
              transfer will not start and curl will return with exit
              code 63.

              A size modifier may be used. For example, Appending 'k' or
              'K' will count the number as kilobytes, 'm' or 'M' makes
              it megabytes, while 'g' or 'G' makes it gigabytes.
              Examples: 200K, 3m and 1G. (Added in 7.58.0)

              NOTE: The file size is not always known prior to download,
              and for such files this option has no effect even if the
              file transfer ends up being larger than this given limit.
              This concerns both FTP and HTTP transfers.

              See also --limit-rate.

       --max-redirs <num>
              (HTTP) Set maximum number of redirection-followings
              allowed. When -L, --location is used, is used to prevent
              curl from following redirections too much. By default, the
              limit is set to 50 redirections. Set this option to -1 to
              make it unlimited.

              If this option is used several times, the last one will be
              used.

       -m, --max-time <seconds>
              Maximum time in seconds that you allow the whole operation
              to take.  This is useful for preventing your batch jobs
              from hanging for hours due to slow networks or links going
              down.  Since 7.32.0, this option accepts decimal values,
              but the actual timeout will decrease in accuracy as the
              specified timeout increases in decimal precision.

              If this option is used several times, the last one will be
              used.

              See also --connect-timeout.

       --metalink
              This option was previously used to specify a metalink
              resource. Metalink support has unfortunately been disabled
              in curl since 7.78.0 due to security reasons.  Added in
              7.27.0.

       --negotiate
              (HTTP) Enables Negotiate (SPNEGO) authentication.

              This option requires a library built with GSS-API or SSPI
              support. Use -V, --version to see if your curl supports
              GSS-API/SSPI or SPNEGO.

              When using this option, you must also provide a fake -u,
              --user option to activate the authentication code
              properly. Sending a '-u :' is enough as the user name and
              password from the -u, --user option aren't actually used.

              If this option is used several times, only the first one
              is used.

              See also --basic, --ntlm, --anyauth and --proxy-negotiate.

       --netrc-file <filename>
              This option is similar to -n, --netrc, except that you
              provide the path (absolute or relative) to the netrc file
              that curl should use.  You can only specify one netrc file
              per invocation. If several --netrc-file options are
              provided, the last one will be used.

              It will abide by --netrc-optional if specified.

              This option overrides -n, --netrc. Added in 7.21.5.

       --netrc-optional
              Very similar to -n, --netrc, but this option makes the
              .netrc usage optional and not mandatory as the -n, --netrc
              option does.

              See also --netrc-file. This option overrides -n, --netrc.

       -n, --netrc
              Makes curl scan the .netrc (_netrc on Windows) file in the
              user's home directory for login name and password. This is
              typically used for FTP on Unix. If used with HTTP, curl
              will enable user authentication. See netrc(5) ftp(1) for
              details on the file format. Curl will not complain if that
              file doesn't have the right permissions (it should not be
              either world- or group-readable). The environment variable
              "HOME" is used to find the home directory.

              A quick and very simple example of how to setup a .netrc
              to allow curl to FTP to the machine host.domain.com with
              user name 'myself' and password 'secret' should look
              similar to:

              machine host.domain.com login myself password secret

       -:, --next
              Tells curl to use a separate operation for the following
              URL and associated options. This allows you to send
              several URL requests, each with their own specific
              options, for example, such as different user names or
              custom requests for each.

              -:, --next will reset all local options and only global
              ones will have their values survive over to the operation
              following the -:, --next instruction. Global options
              include -v, --verbose, --trace, --trace-ascii and --fail-
              early.

              For example, you can do both a GET and a POST in a single
              command line:

               curl www1.example.com --next -d postthis www2.example.com

              Added in 7.36.0.

       --no-alpn
              (HTTPS) Disable the ALPN TLS extension. ALPN is enabled by
              default if libcurl was built with an SSL library that
              supports ALPN. ALPN is used by a libcurl that supports
              HTTP/2 to negotiate HTTP/2 support with the server during
              https sessions.

              See also --no-npn and --http2. --no-alpn requires that the
              underlying libcurl was built to support TLS. Added in
              7.36.0.

       -N, --no-buffer
              Disables the buffering of the output stream. In normal
              work situations, curl will use a standard buffered output
              stream that will have the effect that it will output the
              data in chunks, not necessarily exactly when the data
              arrives.  Using this option will disable that buffering.

              Note that this is the negated option name documented. You
              can thus use --buffer to enforce the buffering.

       --no-keepalive
              Disables the use of keepalive messages on the TCP
              connection. curl otherwise enables them by default.

              Note that this is the negated option name documented. You
              can thus use --keepalive to enforce keepalive.

       --no-npn
              (HTTPS) Disable the NPN TLS extension. NPN is enabled by
              default if libcurl was built with an SSL library that
              supports NPN. NPN is used by a libcurl that supports
              HTTP/2 to negotiate HTTP/2 support with the server during
              https sessions.

              See also --no-alpn and --http2. --no-npn requires that the
              underlying libcurl was built to support TLS. Added in
              7.36.0.

       --no-progress-meter
              Option to switch off the progress meter output without
              muting or otherwise affecting warning and informational
              messages like -s, --silent does.

              Note that this is the negated option name documented. You
              can thus use --progress-meter to enable the progress meter
              again.

              See also -v, --verbose and -s, --silent. Added in 7.67.0.

       --no-sessionid
              (TLS) Disable curl's use of SSL session-ID caching.  By
              default all transfers are done using the cache. Note that
              while nothing should ever get hurt by attempting to reuse
              SSL session-IDs, there seem to be broken SSL
              implementations in the wild that may require you to
              disable this in order for you to succeed.

              Note that this is the negated option name documented. You
              can thus use --sessionid to enforce session-ID caching.

              Added in 7.16.0.

       --noproxy <no-proxy-list>
              Comma-separated list of hosts which do not use a proxy, if
              one is specified.  The only wildcard is a single *
              character, which matches all hosts, and effectively
              disables the proxy. Each name in this list is matched as
              either a domain which contains the hostname, or the
              hostname itself. For example, local.com would match
              local.com, local.com:80, and www.local.com, but not
              www.notlocal.com.

              Since 7.53.0, This option overrides the environment
              variables that disable the proxy. If there's an
              environment variable disabling a proxy, you can set
              noproxy list to "" to override it.

              Added in 7.19.4.

       --ntlm-wb
              (HTTP) Enables NTLM much in the style --ntlm does, but
              hand over the authentication to the separate binary
              ntlmauth application that is executed when needed.

              See also --ntlm and --proxy-ntlm.

       --ntlm (HTTP) Enables NTLM authentication. The NTLM
              authentication method was designed by Microsoft and is
              used by IIS web servers. It is a proprietary protocol,
              reverse-engineered by clever people and implemented in
              curl based on their efforts. This kind of behavior should
              not be endorsed, you should encourage everyone who uses
              NTLM to switch to a public and documented authentication
              method instead, such as Digest.

              If you want to enable NTLM for your proxy authentication,
              then use --proxy-ntlm.

              If this option is used several times, only the first one
              is used.

              See also --proxy-ntlm. --ntlm requires that the underlying
              libcurl was built to support TLS. This option overrides
              --basic and --negotiate and --digest and --anyauth.

       --oauth2-bearer <token>
              (IMAP POP3 SMTP HTTP) Specify the Bearer Token for OAUTH
              2.0 server authentication. The Bearer Token is used in
              conjunction with the user name which can be specified as
              part of the --url or -u, --user options.

              The Bearer Token and user name are formatted according to
              RFC 6750.

              If this option is used several times, the last one will be
              used.

       --output-dir <dir>

              This option specifies the directory in which files should
              be stored, when -O, --remote-name or -o, --output are
              used.

              The given output directory is used for all URLs and output
              options on the command line, up until the first -:,
              --next.

              If the specified target directory doesn't exist, the
              operation will fail unless --create-dirs is also used.

              If this option is used multiple times, the last specified
              directory will be used.

              See also -O, --remote-name and -J, --remote-header-name.
              Added in 7.73.0.

       -o, --output <file>
              Write output to <file> instead of stdout. If you are using
              {} or [] to fetch multiple documents, you should quote the
              URL and you can use '#' followed by a number in the <file>
              specifier. That variable will be replaced with the current
              string for the URL being fetched. Like in:

               curl "http://{one,two}.example.com" -o "file_#1.txt"

              or use several variables like:

               curl "http://{site,host}.host[1-5].com" -o "#1_#2"

              You may use this option as many times as the number of
              URLs you have. For example, if you specify two URLs on the
              same command line, you can use it like this:

                curl -o aa example.com -o bb example.net

              and the order of the -o options and the URLs doesn't
              matter, just that the first -o is for the first URL and so
              on, so the above command line can also be written as

                curl example.com example.net -o aa -o bb

              See also the --create-dirs option to create the local
              directories dynamically. Specifying the output as '-' (a
              single dash) will force the output to be done to stdout.

              See also -O, --remote-name, --remote-name-all and -J,
              --remote-header-name.

       --parallel-immediate
              When doing parallel transfers, this option will instruct
              curl that it should rather prefer opening up more
              connections in parallel at once rather than waiting to see
              if new transfers can be added as multiplexed streams on
              another connection.

              See also -Z, --parallel and --parallel-max. Added in
              7.68.0.

       --parallel-max
              When asked to do parallel transfers, using -Z, --parallel,
              this option controls the maximum amount of transfers to do
              simultaneously.

              The default is 50.

              See also -Z, --parallel. Added in 7.66.0.

       -Z, --parallel
              Makes curl perform its transfers in parallel as compared
              to the regular serial manner.

              Added in 7.66.0.

       --pass <phrase>
              (SSH TLS) Passphrase for the private key

              If this option is used several times, the last one will be
              used.

       --path-as-is
              Tell curl to not handle sequences of /../ or /./ in the
              given URL path. Normally curl will squash or merge them
              according to standards but with this option set you tell
              it not to do that.

              Added in 7.42.0.

       --pinnedpubkey <hashes>
              (TLS) Tells curl to use the specified public key file (or
              hashes) to verify the peer. This can be a path to a file
              which contains a single public key in PEM or DER format,
              or any number of base64 encoded sha256 hashes preceded by
              ´sha256//´ and separated by ´;´

              When negotiating a TLS or SSL connection, the server sends
              a certificate indicating its identity. A public key is
              extracted from this certificate and if it does not exactly
              match the public key provided to this option, curl will
              abort the connection before sending or receiving any data.

              PEM/DER support:
                7.39.0: OpenSSL, GnuTLS and GSKit
                7.43.0: NSS and wolfSSL
                7.47.0: mbedtls sha256 support:
                7.44.0: OpenSSL, GnuTLS, NSS and wolfSSL
                7.47.0: mbedtls Other SSL backends not supported.

              If this option is used several times, the last one will be
              used.

       --post301
              (HTTP) Tells curl to respect RFC 7231/6.4.2 and not
              convert POST requests into GET requests when following a
              301 redirection. The non-RFC behavior is ubiquitous in web
              browsers, so curl does the conversion by default to
              maintain consistency. However, a server may require a POST
              to remain a POST after such a redirection. This option is
              meaningful only when using -L, --location.

              See also --post302, --post303 and -L, --location. Added in
              7.17.1.

       --post302
              (HTTP) Tells curl to respect RFC 7231/6.4.3 and not
              convert POST requests into GET requests when following a
              302 redirection. The non-RFC behavior is ubiquitous in web
              browsers, so curl does the conversion by default to
              maintain consistency. However, a server may require a POST
              to remain a POST after such a redirection. This option is
              meaningful only when using -L, --location.

              See also --post301, --post303 and -L, --location. Added in
              7.19.1.

       --post303
              (HTTP) Tells curl to violate RFC 7231/6.4.4 and not
              convert POST requests into GET requests when following 303
              redirections. A server may require a POST to remain a POST
              after a 303 redirection. This option is meaningful only
              when using -L, --location.

              See also --post302, --post301 and -L, --location. Added in
              7.26.0.

       --preproxy [protocol://]host[:port]
              Use the specified SOCKS proxy before connecting to an HTTP
              or HTTPS -x, --proxy. In such a case curl first connects
              to the SOCKS proxy and then connects (through SOCKS) to
              the HTTP or HTTPS proxy. Hence pre proxy.

              The pre proxy string should be specified with a
              protocol:// prefix to specify alternative proxy protocols.
              Use socks4://, socks4a://, socks5:// or socks5h:// to
              request the specific SOCKS version to be used. No protocol
              specified will make curl default to SOCKS4.

              If the port number is not specified in the proxy string,
              it is assumed to be 1080.

              User and password that might be provided in the proxy
              string are URL decoded by curl. This allows you to pass in
              special characters such as @ by using %40 or pass in a
              colon with %3a.

              If this option is used several times, the last one will be
              used.

              Added in 7.52.0.

       -#, --progress-bar
              Make curl display transfer progress as a simple progress
              bar instead of the standard, more informational, meter.

              This progress bar draws a single line of '#' characters
              across the screen and shows a percentage if the transfer
              size is known. For transfers without a known size, there
              will be space ship (-=o=-) that moves back and forth but
              only while data is being transferred, with a set of flying
              hash sign symbols on top.

       --proto-default <protocol>
              Tells curl to use protocol for any URL missing a scheme
              name.

              Example:

               curl --proto-default https ftp.mozilla.org

              An unknown or unsupported protocol causes error
              CURLE_UNSUPPORTED_PROTOCOL (1).

              This option does not change the default proxy protocol
              (http).

              Without this option curl would make a guess based on the
              host, see --url for details.

              Added in 7.45.0.

       --proto-redir <protocols>
              Tells curl to limit what protocols it may use on redirect.
              Protocols denied by --proto are not overridden by this
              option. See --proto for how protocols are represented.

              Example, allow only HTTP and HTTPS on redirect:

               curl --proto-redir -all,http,https http://example.com

              By default curl will allow HTTP, HTTPS, FTP and FTPS on
              redirect (7.65.2).  Older versions of curl allowed all
              protocols on redirect except several disabled for security
              reasons: Since 7.19.4 FILE and SCP are disabled, and since
              7.40.0 SMB and SMBS are also disabled. Specifying all or
              +all enables all protocols on redirect, including those
              disabled for security.

              Added in 7.20.2.

       --proto <protocols>
              Tells curl to limit what protocols it may use in the
              transfer. Protocols are evaluated left to right, are comma
              separated, and are each a protocol name or 'all',
              optionally prefixed by zero or more modifiers. Available
              modifiers are:

              +  Permit this protocol in addition to protocols already
                 permitted (this is the default if no modifier is used).

              -  Deny this protocol, removing it from the list of
                 protocols already permitted.

              =  Permit only this protocol (ignoring the list already
                 permitted), though subject to later modification by
                 subsequent entries in the comma separated list.

              For example:

              --proto -ftps
                     uses the default protocols, but disables ftps

              --proto -all,https,+http
                     only enables http and https

              --proto =http,https
                     also only enables http and https

       Unknown protocols produce a warning. This allows scripts to
       safely rely on being able to disable potentially dangerous
       protocols, without relying upon support for that protocol being
       built into curl to avoid an error.

       This option can be used multiple times, in which case the effect
       is the same as concatenating the protocols into one instance of
       the option.

       See also --proto-redir and --proto-default. Added in 7.20.2.

       --proxy-anyauth
              Tells curl to pick a suitable authentication method when
              communicating with the given HTTP proxy. This might cause
              an extra request/response round-trip.

              See also -x, --proxy, --proxy-basic and --proxy-digest.
              Added in 7.13.2.

       --proxy-basic
              Tells curl to use HTTP Basic authentication when
              communicating with the given proxy. Use --basic for
              enabling HTTP Basic with a remote host. Basic is the
              default authentication method curl uses with proxies.

              See also -x, --proxy, --proxy-anyauth and --proxy-digest.

       --proxy-cacert <file>
              Same as --cacert but used in HTTPS proxy context.

              See also --proxy-capath, --cacert, --capath and -x,
              --proxy. Added in 7.52.0.

       --proxy-capath <dir>
              Same as --capath but used in HTTPS proxy context.

              See also --proxy-cacert, -x, --proxy and --capath. Added
              in 7.52.0.

       --proxy-cert-type <type>
              Same as --cert-type but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-cert <cert[:passwd]>
              Same as -E, --cert but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-ciphers <list>
              Same as --ciphers but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-crlfile <file>
              Same as --crlfile but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-digest
              Tells curl to use HTTP Digest authentication when
              communicating with the given proxy. Use --digest for
              enabling HTTP Digest with a remote host.

              See also -x, --proxy, --proxy-anyauth and --proxy-basic.

       --proxy-header <header/@file>
              (HTTP) Extra header to include in the request when sending
              HTTP to a proxy. You may specify any number of extra
              headers. This is the equivalent option to -H, --header but
              is for proxy communication only like in CONNECT requests
              when you want a separate header sent to the proxy to what
              is sent to the actual remote host.

              curl will make sure that each header you add/replace is
              sent with the proper end-of-line marker, you should thus
              not add that as a part of the header content: do not add
              newlines or carriage returns, they will only mess things
              up for you.

              Headers specified with this option will not be included in
              requests that curl knows will not be sent to a proxy.

              Starting in 7.55.0, this option can take an argument in
              @filename style, which then adds a header for each line in
              the input file. Using @- will make curl read the header
              file from stdin.

              This option can be used multiple times to
              add/replace/remove multiple headers.

              Added in 7.37.0.

       --proxy-insecure
              Same as -k, --insecure but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-key-type <type>
              Same as --key-type but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-key <key>
              Same as --key but used in HTTPS proxy context.

       --proxy-negotiate
              Tells curl to use HTTP Negotiate (SPNEGO) authentication
              when communicating with the given proxy. Use --negotiate
              for enabling HTTP Negotiate (SPNEGO) with a remote host.

              See also --proxy-anyauth and --proxy-basic. Added in
              7.17.1.

       --proxy-ntlm
              Tells curl to use HTTP NTLM authentication when
              communicating with the given proxy. Use --ntlm for
              enabling NTLM with a remote host.

              See also --proxy-negotiate and --proxy-anyauth.

       --proxy-pass <phrase>
              Same as --pass but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-pinnedpubkey <hashes>
              (TLS) Tells curl to use the specified public key file (or
              hashes) to verify the proxy. This can be a path to a file
              which contains a single public key in PEM or DER format,
              or any number of base64 encoded sha256 hashes preceded by
              ´sha256//´ and separated by ´;´

              When negotiating a TLS or SSL connection, the server sends
              a certificate indicating its identity. A public key is
              extracted from this certificate and if it does not exactly
              match the public key provided to this option, curl will
              abort the connection before sending or receiving any data.

              If this option is used several times, the last one will be
              used.

       --proxy-service-name <name>
              This option allows you to change the service name for
              proxy negotiation.

              Added in 7.43.0.

       --proxy-ssl-allow-beast
              Same as --ssl-allow-beast but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-ssl-auto-client-cert
              Same as --ssl-auto-client-cert but used in HTTPS proxy
              context.

              Added in 7.77.0.

       --proxy-tls13-ciphers <ciphersuite list>
              (TLS) Specifies which cipher suites to use in the
              connection to your HTTPS proxy when it negotiates TLS 1.3.
              The list of ciphers suites must specify valid ciphers.
              Read up on TLS 1.3 cipher suite details on this URL:

               https://curl.se/docs/ssl-ciphers.html

              This option is currently used only when curl is built to
              use OpenSSL 1.1.1 or later. If you are using a different
              SSL backend you can try setting TLS 1.3 cipher suites by
              using the --proxy-ciphers option.

              If this option is used several times, the last one will be
              used.

       --proxy-tlsauthtype <type>
              Same as --tlsauthtype but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-tlspassword <string>
              Same as --tlspassword but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-tlsuser <name>
              Same as --tlsuser but used in HTTPS proxy context.

              Added in 7.52.0.

       --proxy-tlsv1
              Same as -1, --tlsv1 but used in HTTPS proxy context.

              Added in 7.52.0.

       -U, --proxy-user <user:password>
              Specify the user name and password to use for proxy
              authentication.

              If you use a Windows SSPI-enabled curl binary and do
              either Negotiate or NTLM authentication then you can tell
              curl to select the user name and password from your
              environment by specifying a single colon with this option:
              "-U :".

              On systems where it works, curl will hide the given option
              argument from process listings. This is not enough to
              protect credentials from possibly getting seen by other
              users on the same system as they will still be visible for
              a brief moment before cleared. Such sensitive data should
              be retrieved from a file instead or similar and never used
              in clear text in a command line.

              If this option is used several times, the last one will be
              used.

       -x, --proxy [protocol://]host[:port]
              Use the specified proxy.

              The proxy string can be specified with a protocol://
              prefix. No protocol specified or http:// will be treated
              as HTTP proxy. Use socks4://, socks4a://, socks5:// or
              socks5h:// to request a specific SOCKS version to be used.
              (The protocol support was added in curl 7.21.7)

              HTTPS proxy support via https:// protocol prefix was added
              in 7.52.0 for OpenSSL, GnuTLS and NSS.

              Unrecognized and unsupported proxy protocols cause an
              error since 7.52.0.  Prior versions may ignore the
              protocol and use http:// instead.

              If the port number is not specified in the proxy string,
              it is assumed to be 1080.

              This option overrides existing environment variables that
              set the proxy to use. If there's an environment variable
              setting a proxy, you can set proxy to "" to override it.

              All operations that are performed over an HTTP proxy will
              transparently be converted to HTTP. It means that certain
              protocol specific operations might not be available. This
              is not the case if you can tunnel through the proxy, as
              one with the -p, --proxytunnel option.

              User and password that might be provided in the proxy
              string are URL decoded by curl. This allows you to pass in
              special characters such as @ by using %40 or pass in a
              colon with %3a.

              The proxy host can be specified the exact same way as the
              proxy environment variables, including the protocol prefix
              (http://) and the embedded user + password.

              If this option is used several times, the last one will be
              used.

       --proxy1.0 <host[:port]>
              Use the specified HTTP 1.0 proxy. If the port number is
              not specified, it is assumed at port 1080.

              The only difference between this and the HTTP proxy option
              -x, --proxy, is that attempts to use CONNECT through the
              proxy will specify an HTTP 1.0 protocol instead of the
              default HTTP 1.1.

       -p, --proxytunnel
              When an HTTP proxy is used -x, --proxy, this option will
              make curl tunnel through the proxy. The tunnel approach is
              made with the HTTP proxy CONNECT request and requires that
              the proxy allows direct connect to the remote port number
              curl wants to tunnel through to.

              To suppress proxy CONNECT response headers when curl is
              set to output headers use --suppress-connect-headers.

              See also -x, --proxy.

       --pubkey <key>
              (SFTP SCP) Public key file name. Allows you to provide
              your public key in this separate file.

              If this option is used several times, the last one will be
              used.

              (As of 7.39.0, curl attempts to automatically extract the
              public key from the private key file, so passing this
              option is generally not required. Note that this public
              key extraction requires libcurl to be linked against a
              copy of libssh2 1.2.8 or higher that is itself linked
              against OpenSSL.)

       -Q, --quote
              (FTP SFTP) Send an arbitrary command to the remote FTP or
              SFTP server. Quote commands are sent BEFORE the transfer
              takes place (just after the initial PWD command in an FTP
              transfer, to be exact). To make commands take place after
              a successful transfer, prefix them with a dash '-'.  To
              make commands be sent after curl has changed the working
              directory, just before the transfer command(s), prefix the
              command with a '+' (this is only supported for FTP). You
              may specify any number of commands.

              If the server returns failure for one of the commands, the
              entire operation will be aborted. You must send
              syntactically correct FTP commands as RFC 959 defines to
              FTP servers, or one of the commands listed below to SFTP
              servers.

              Prefix the command with an asterisk (*) to make curl
              continue even if the command fails as by default curl will
              stop at first failure.

              This option can be used multiple times.

              SFTP is a binary protocol. Unlike for FTP, curl interprets
              SFTP quote commands itself before sending them to the
              server.  File names may be quoted shell-style to embed
              spaces or special characters.  Following is the list of
              all supported SFTP quote commands:

              atime date file
                     The atime command sets the last access time of the
                     file named by the file operand. The <date
                     expression> can be all sorts of date strings, see
                     the curl_getdate(3) man page for date expression
                     details. (Added in 7.73.0)

              chgrp group file
                     The chgrp command sets the group ID of the file
                     named by the file operand to the group ID specified
                     by the group operand. The group operand is a
                     decimal integer group ID.

              chmod mode file
                     The chmod command modifies the file mode bits of
                     the specified file. The mode operand is an octal
                     integer mode number.

              chown user file
                     The chown command sets the owner of the file named
                     by the file operand to the user ID specified by the
                     user operand. The user operand is a decimal integer
                     user ID.

              ln source_file target_file
                     The ln and symlink commands create a symbolic link
                     at the target_file location pointing to the
                     source_file location.

              mkdir directory_name
                     The mkdir command creates the directory named by
                     the directory_name operand.

              mtime date file
                     The mtime command sets the last modification time
                     of the file named by the file operand. The <date
                     expression> can be all sorts of date strings, see
                     the curl_getdate(3) man page for date expression
                     details. (Added in 7.73.0)

              pwd    The pwd command returns the absolute pathname of
                     the current working directory.

              rename source target
                     The rename command renames the file or directory
                     named by the source operand to the destination path
                     named by the target operand.

              rm file
                     The rm command removes the file specified by the
                     file operand.

              rmdir directory
                     The rmdir command removes the directory entry
                     specified by the directory operand, provided it is
                     empty.

              symlink source_file target_file
                     See ln.

       --random-file <file>
              Specify the path name to file containing what will be
              considered as random data. The data may be used to seed
              the random engine for SSL connections.  See also the
              --egd-file option.

       -r, --range <range>
              (HTTP FTP SFTP FILE) Retrieve a byte range (i.e. a partial
              document) from an HTTP/1.1, FTP or SFTP server or a local
              FILE. Ranges can be specified in a number of ways.

              0-499  specifies the first 500 bytes

              500-999
                     specifies the second 500 bytes

              -500   specifies the last 500 bytes

              9500-  specifies the bytes from offset 9500 and forward

              0-0,-1 specifies the first and last byte only(*)(HTTP)

              100-199,500-599
                     specifies two separate 100-byte ranges(*) (HTTP)

              (*) = NOTE that this will cause the server to reply with a
              multipart response, which will be returned as-is by curl!
              Parsing or otherwise transforming this response is the
              responsibility of the caller.

              Only digit characters (0-9) are valid in the 'start' and
              'stop' fields of the 'start-stop' range syntax. If a non-
              digit character is given in the range, the server's
              response will be unspecified, depending on the server's
              configuration.

              You should also be aware that many HTTP/1.1 servers do not
              have this feature enabled, so that when you attempt to get
              a range, you'll instead get the whole document.

              FTP and SFTP range downloads only support the simple
              'start-stop' syntax (optionally with one of the numbers
              omitted). FTP use depends on the extended FTP command
              SIZE.

              If this option is used several times, the last one will be
              used.

       --raw  (HTTP) When used, it disables all internal HTTP decoding
              of content or transfer encodings and instead makes them
              passed on unaltered, raw.

              Added in 7.16.2.

       -e, --referer <URL>
              (HTTP) Sends the "Referrer Page" information to the HTTP
              server. This can also be set with the -H, --header flag of
              course.  When used with -L, --location you can append
              ";auto" to the -e, --referer URL to make curl
              automatically set the previous URL when it follows a
              Location: header. The ";auto" string can be used alone,
              even if you don't set an initial -e, --referer.

              If this option is used several times, the last one will be
              used.

              See also -A, --user-agent and -H, --header.

       -J, --remote-header-name
              (HTTP) This option tells the -O, --remote-name option to
              use the server-specified Content-Disposition filename
              instead of extracting a filename from the URL.

              If the server specifies a file name and a file with that
              name already exists in the current working directory it
              will not be overwritten and an error will occur. If the
              server doesn't specify a file name then this option has no
              effect.

              There's no attempt to decode %-sequences (yet) in the
              provided file name, so this option may provide you with
              rather unexpected file names.

              WARNING: Exercise judicious use of this option, especially
              on Windows. A rogue server could send you the name of a
              DLL or other file that could possibly be loaded
              automatically by Windows or some third party software.

       --remote-name-all
              This option changes the default action for all given URLs
              to be dealt with as if -O, --remote-name were used for
              each one. So if you want to disable that for a specific
              URL after --remote-name-all has been used, you must use
              "-o -" or --no-remote-name.

              Added in 7.19.0.

       -O, --remote-name
              Write output to a local file named like the remote file we
              get. (Only the file part of the remote file is used, the
              path is cut off.)

              The file will be saved in the current working directory.
              If you want the file saved in a different directory, make
              sure you change the current working directory before
              invoking curl with this option.

              The remote file name to use for saving is extracted from
              the given URL, nothing else, and if it already exists it
              will be overwritten. If you want the server to be able to
              choose the file name refer to -J, --remote-header-name
              which can be used in addition to this option. If the
              server chooses a file name and that name already exists it
              will not be overwritten.

              There is no URL decoding done on the file name. If it has
              %20 or other URL encoded parts of the name, they will end
              up as-is as file name.

              You may use this option as many times as the number of
              URLs you have.

       -R, --remote-time
              When used, this will make curl attempt to figure out the
              timestamp of the remote file, and if that is available
              make the local file get that same timestamp.

       --request-target
              (HTTP) Tells curl to use an alternative "target" (path)
              instead of using the path as provided in the URL.
              Particularly useful when wanting to issue HTTP requests
              without leading slash or other data that doesn't follow
              the regular URL pattern, like "OPTIONS *".

              Added in 7.55.0.

       -X, --request <command>
              (HTTP) Specifies a custom request method to use when
              communicating with the HTTP server.  The specified request
              method will be used instead of the method otherwise used
              (which defaults to GET). Read the HTTP 1.1 specification
              for details and explanations. Common additional HTTP
              requests include PUT and DELETE, but related technologies
              like WebDAV offers PROPFIND, COPY, MOVE and more.

              Normally you don't need this option. All sorts of GET,
              HEAD, POST and PUT requests are rather invoked by using
              dedicated command line options.

              This option only changes the actual word used in the HTTP
              request, it does not alter the way curl behaves. So for
              example if you want to make a proper HEAD request, using
              -X HEAD will not suffice. You need to use the -I, --head
              option.

              The method string you set with -X, --request will be used
              for all requests, which if you for example use -L,
              --location may cause unintended side-effects when curl
              doesn't change request method according to the HTTP 30x
              response codes - and similar.

              (FTP) Specifies a custom FTP command to use instead of
              LIST when doing file lists with FTP.

              (POP3) Specifies a custom POP3 command to use instead of
              LIST or RETR. (Added in 7.26.0)

              (IMAP) Specifies a custom IMAP command to use instead of
              LIST. (Added in 7.30.0)

              (SMTP) Specifies a custom SMTP command to use instead of
              HELP or VRFY. (Added in 7.34.0)

              If this option is used several times, the last one will be
              used.

       --resolve <[+]host:port:addr[,addr]...>
              Provide a custom address for a specific host and port
              pair. Using this, you can make the curl requests(s) use a
              specified address and prevent the otherwise normally
              resolved address to be used. Consider it a sort of
              /etc/hosts alternative provided on the command line. The
              port number should be the number used for the specific
              protocol the host will be used for. It means you need
              several entries if you want to provide address for the
              same host but different ports.

              By specifying '*' as host you can tell curl to resolve any
              host and specific port pair to the specified address.
              Wildcard is resolved last so any --resolve with a specific
              host and port will be used first.

              The provided address set by this option will be used even
              if -4, --ipv4 or -6, --ipv6 is set to make curl use
              another IP version.

              By prefixing the host with a '+' you can make the entry
              time out after curl's default timeout (1 minute). Note
              that this will only make sense for long running parallel
              transfers with a lot of files. In such cases, if this
              option is used curl will try to resolve the host as it
              normally would once the timeout has expired.

              Support for providing the IP address within [brackets] was
              added in 7.57.0.

              Support for providing multiple IP addresses per entry was
              added in 7.59.0.

              Support for resolving with wildcard was added in 7.64.0.

              Support for the '+' prefix was was added in 7.75.0.

              This option can be used many times to add many host names
              to resolve.

              Added in 7.21.3.

       --retry-all-errors
              Retry on any error. This option is used together with
              --retry.

              This option is the "sledgehammer" of retrying. Do not use
              this option by default (eg in curlrc), there may be
              unintended consequences such as sending or receiving
              duplicate data. Do not use with redirected input or
              output. You'd be much better off handling your unique
              problems in shell script. Please read the example below.

              Warning: For server compatibility curl attempts to retry
              failed flaky transfers as close as possible to how they
              were started, but this is not possible with redirected
              input or output. For example, before retrying it removes
              output data from a failed partial transfer that was
              written to an output file. However this is not true of
              data redirected to a | pipe or > file, which are not
              reset. We strongly suggest don't parse or record output
              via redirect in combination with this option, since you
              may receive duplicate data.

              By default curl will not error on an HTTP response code
              that indicates an HTTP error, if the transfer was
              successful. For example, if a server replies 404 Not Found
              and the reply is fully received then that is not an error.
              When --retry is used then curl will retry on some HTTP
              response codes that indicate transient HTTP errors, but
              that does not include most 4xx response codes such as 404.
              If you want to retry on all response codes that indicate
              HTTP errors (4xx and 5xx) then combine with -f, --fail.

              Added in 7.71.0.

       --retry-connrefused
              In addition to the other conditions, consider ECONNREFUSED
              as a transient error too for --retry. This option is used
              together with --retry.

              Added in 7.52.0.

       --retry-delay <seconds>
              Make curl sleep this amount of time before each retry when
              a transfer has failed with a transient error (it changes
              the default backoff time algorithm between retries). This
              option is only interesting if --retry is also used.
              Setting this delay to zero will make curl use the default
              backoff time.

              If this option is used several times, the last one will be
              used.

              Added in 7.12.3.

       --retry-max-time <seconds>
              The retry timer is reset before the first transfer
              attempt. Retries will be done as usual (see --retry) as
              long as the timer hasn't reached this given limit. Notice
              that if the timer hasn't reached the limit, the request
              will be made and while performing, it may take longer than
              this given time period. To limit a single request´s
              maximum time, use -m, --max-time.  Set this option to zero
              to not timeout retries.

              If this option is used several times, the last one will be
              used.

              Added in 7.12.3.

       --retry <num>
              If a transient error is returned when curl tries to
              perform a transfer, it will retry this number of times
              before giving up. Setting the number to 0 makes curl do no
              retries (which is the default). Transient error means
              either: a timeout, an FTP 4xx response code or an HTTP
              408, 429, 500, 502, 503 or 504 response code.

              When curl is about to retry a transfer, it will first wait
              one second and then for all forthcoming retries it will
              double the waiting time until it reaches 10 minutes which
              then will be the delay between the rest of the retries.
              By using --retry-delay you disable this exponential
              backoff algorithm. See also --retry-max-time to limit the
              total time allowed for retries.

              Since curl 7.66.0, curl will comply with the Retry-After:
              response header if one was present to know when to issue
              the next retry.

              If this option is used several times, the last one will be
              used.

              Added in 7.12.3.

       --sasl-authzid <identity>
              Use this authorisation identity (authzid), during SASL
              PLAIN authentication, in addition to the authentication
              identity (authcid) as specified by -u, --user.

              If the option isn't specified, the server will derive the
              authzid from the authcid, but if specified, and depending
              on the server implementation, it may be used to access
              another user's inbox, that the user has been granted
              access to, or a shared mailbox for example.

              Added in 7.66.0.

       --sasl-ir
              Enable initial response in SASL authentication.

              Added in 7.31.0.

       --service-name <name>
              This option allows you to change the service name for
              SPNEGO.

              Examples: --negotiate --service-name sockd would use
              sockd/server-name.

              Added in 7.43.0.

       -S, --show-error
              When used with -s, --silent, it makes curl show an error
              message if it fails.

              See also --no-progress-meter.

       -s, --silent
              Silent or quiet mode. Don't show progress meter or error
              messages.  Makes Curl mute. It will still output the data
              you ask for, potentially even to the terminal/stdout
              unless you redirect it.

              Use -S, --show-error in addition to this option to disable
              progress meter but still show error messages.

              See also -v, --verbose, --stderr and --no-progress-meter.

       --socks4 <host[:port]>
              Use the specified SOCKS4 proxy. If the port number is not
              specified, it is assumed at port 1080. Using this socket
              type make curl resolve the host name and passing the
              address on to the proxy.

              This option overrides any previous use of -x, --proxy, as
              they are mutually exclusive.

              Since 7.21.7, this option is superfluous since you can
              specify a socks4 proxy with -x, --proxy using a socks4://
              protocol prefix.

              Since 7.52.0, --preproxy can be used to specify a SOCKS
              proxy at the same time -x, --proxy is used with an
              HTTP/HTTPS proxy. In such a case curl first connects to
              the SOCKS proxy and then connects (through SOCKS) to the
              HTTP or HTTPS proxy.

              If this option is used several times, the last one will be
              used.

              Added in 7.15.2.

       --socks4a <host[:port]>
              Use the specified SOCKS4a proxy. If the port number is not
              specified, it is assumed at port 1080. This asks the proxy
              to resolve the host name.

              This option overrides any previous use of -x, --proxy, as
              they are mutually exclusive.

              Since 7.21.7, this option is superfluous since you can
              specify a socks4a proxy with -x, --proxy using a
              socks4a:// protocol prefix.

              Since 7.52.0, --preproxy can be used to specify a SOCKS
              proxy at the same time -x, --proxy is used with an
              HTTP/HTTPS proxy. In such a case curl first connects to
              the SOCKS proxy and then connects (through SOCKS) to the
              HTTP or HTTPS proxy.

              If this option is used several times, the last one will be
              used.

              Added in 7.18.0.

       --socks5-basic
              Tells curl to use username/password authentication when
              connecting to a SOCKS5 proxy.  The username/password
              authentication is enabled by default.  Use --socks5-gssapi
              to force GSS-API authentication to SOCKS5 proxies.

              Added in 7.55.0.

       --socks5-gssapi-nec
              As part of the GSS-API negotiation a protection mode is
              negotiated. RFC 1961 says in section 4.3/4.4 it should be
              protected, but the NEC reference implementation does not.
              The option --socks5-gssapi-nec allows the unprotected
              exchange of the protection mode negotiation.

              Added in 7.19.4.

       --socks5-gssapi-service <name>
              The default service name for a socks server is
              rcmd/server-fqdn. This option allows you to change it.

              Examples: --socks5 proxy-name --socks5-gssapi-service
              sockd would use sockd/proxy-name --socks5 proxy-name
              --socks5-gssapi-service sockd/real-name would use
              sockd/real-name for cases where the proxy-name does not
              match the principal name.

              Added in 7.19.4.

       --socks5-gssapi
              Tells curl to use GSS-API authentication when connecting
              to a SOCKS5 proxy.  The GSS-API authentication is enabled
              by default (if curl is compiled with GSS-API support).
              Use --socks5-basic to force username/password
              authentication to SOCKS5 proxies.

              Added in 7.55.0.

       --socks5-hostname <host[:port]>
              Use the specified SOCKS5 proxy (and let the proxy resolve
              the host name). If the port number is not specified, it is
              assumed at port 1080.

              This option overrides any previous use of -x, --proxy, as
              they are mutually exclusive.

              Since 7.21.7, this option is superfluous since you can
              specify a socks5 hostname proxy with -x, --proxy using a
              socks5h:// protocol prefix.

              Since 7.52.0, --preproxy can be used to specify a SOCKS
              proxy at the same time -x, --proxy is used with an
              HTTP/HTTPS proxy. In such a case curl first connects to
              the SOCKS proxy and then connects (through SOCKS) to the
              HTTP or HTTPS proxy.

              If this option is used several times, the last one will be
              used.

              Added in 7.18.0.

       --socks5 <host[:port]>
              Use the specified SOCKS5 proxy - but resolve the host name
              locally. If the port number is not specified, it is
              assumed at port 1080.

              This option overrides any previous use of -x, --proxy, as
              they are mutually exclusive.

              Since 7.21.7, this option is superfluous since you can
              specify a socks5 proxy with -x, --proxy using a socks5://
              protocol prefix.

              Since 7.52.0, --preproxy can be used to specify a SOCKS
              proxy at the same time -x, --proxy is used with an
              HTTP/HTTPS proxy. In such a case curl first connects to
              the SOCKS proxy and then connects (through SOCKS) to the
              HTTP or HTTPS proxy.

              If this option is used several times, the last one will be
              used.

              This option (as well as --socks4) does not work with IPV6,
              FTPS or LDAP.

              Added in 7.18.0.

       -Y, --speed-limit <speed>
              If a download is slower than this given speed (in bytes
              per second) for speed-time seconds it gets aborted. speed-
              time is set with -y, --speed-time and is 30 if not set.

              If this option is used several times, the last one will be
              used.

       -y, --speed-time <seconds>
              If a download is slower than speed-limit bytes per second
              during a speed-time period, the download gets aborted. If
              speed-time is used, the default speed-limit will be 1
              unless set with -Y, --speed-limit.

              This option controls transfers and thus will not affect
              slow connects etc. If this is a concern for you, try the
              --connect-timeout option.

              If this option is used several times, the last one will be
              used.

       --ssl-allow-beast
              This option tells curl to not work around a security flaw
              in the SSL3 and TLS1.0 protocols known as BEAST.  If this
              option isn't used, the SSL layer may use workarounds known
              to cause interoperability problems with some older SSL
              implementations. WARNING: this option loosens the SSL
              security, and by using this flag you ask for exactly that.

              Added in 7.25.0.

       --ssl-auto-client-cert
              Tell libcurl to automatically locate and use a client
              certificate for authentication, when requested by the
              server. This option is only supported for Schannel (the
              native Windows SSL library). Prior to 7.77.0 this was the
              default behavior in libcurl with Schannel. Since the
              server can request any certificate that supports client
              authentication in the OS certificate store it could be a
              privacy violation and unexpected.

              See also --proxy-ssl-auto-client-cert. Added in 7.77.0.

       --ssl-no-revoke
              (Schannel) This option tells curl to disable certificate
              revocation checks.  WARNING: this option loosens the SSL
              security, and by using this flag you ask for exactly that.

              Added in 7.44.0.

       --ssl-reqd
              (FTP IMAP POP3 SMTP) Require SSL/TLS for the connection.
              Terminates the connection if the server doesn't support
              SSL/TLS.

              This option was formerly known as --ftp-ssl-reqd.

              Added in 7.20.0.

       --ssl-revoke-best-effort
              (Schannel) This option tells curl to ignore certificate
              revocation checks when they failed due to missing/offline
              distribution points for the revocation check lists.

              Added in 7.70.0.

       --ssl  (FTP IMAP POP3 SMTP) Try to use SSL/TLS for the
              connection.  Reverts to a non-secure connection if the
              server doesn't support SSL/TLS.  See also --ftp-ssl-
              control and --ssl-reqd for different levels of encryption
              required.

              This option was formerly known as --ftp-ssl (Added in
              7.11.0). That option name can still be used but will be
              removed in a future version.

              Added in 7.20.0.

       -2, --sslv2
              (SSL) This option previously asked curl to use SSLv2, but
              starting in curl 7.77.0 this instruction is ignored. SSLv2
              is widely considered insecure (see RFC 6176).

              See also --http1.1 and --http2. -2, --sslv2 requires that
              the underlying libcurl was built to support TLS. This
              option overrides -3, --sslv3 and -1, --tlsv1 and --tlsv1.1
              and --tlsv1.2.

       -3, --sslv3
              (SSL) This option previously asked curl to use SSLv3, but
              starting in curl 7.77.0 this instruction is ignored. SSLv3
              is widely considered insecure (see RFC 7568).

              See also --http1.1 and --http2. -3, --sslv3 requires that
              the underlying libcurl was built to support TLS. This
              option overrides -2, --sslv2 and -1, --tlsv1 and --tlsv1.1
              and --tlsv1.2.

       --stderr <file>
              Redirect all writes to stderr to the specified file
              instead. If the file name is a plain '-', it is instead
              written to stdout.

              If this option is used several times, the last one will be
              used.

              See also -v, --verbose and -s, --silent.

       --styled-output
              Enables the automatic use of bold font styles when writing
              HTTP headers to the terminal. Use --no-styled-output to
              switch them off.

              Added in 7.61.0.

       --suppress-connect-headers
              When -p, --proxytunnel is used and a CONNECT request is
              made don't output proxy CONNECT response headers. This
              option is meant to be used with -D, --dump-header or -i,
              --include which are used to show protocol headers in the
              output. It has no effect on debug options such as -v,
              --verbose or --trace, or any statistics.

              See also -D, --dump-header, -i, --include and -p,
              --proxytunnel.

       --tcp-fastopen
              Enable use of TCP Fast Open (RFC7413).

              Added in 7.49.0.

       --tcp-nodelay
              Turn on the TCP_NODELAY option. See the
              curl_easy_setopt(3) man page for details about this
              option.

              Since 7.50.2, curl sets this option by default and you
              need to explicitly switch it off if you don't want it on.

              Added in 7.11.2.

       -t, --telnet-option <opt=val>
              Pass options to the telnet protocol. Supported options
              are:

              TTYPE=<term> Sets the terminal type.

              XDISPLOC=<X display> Sets the X display location.

              NEW_ENV=<var,val> Sets an environment variable.

       --tftp-blksize <value>
              (TFTP) Set TFTP BLKSIZE option (must be >512). This is the
              block size that curl will try to use when transferring
              data to or from a TFTP server. By default 512 bytes will
              be used.

              If this option is used several times, the last one will be
              used.

              Added in 7.20.0.

       --tftp-no-options
              (TFTP) Tells curl not to send TFTP options requests.

              This option improves interop with some legacy servers that
              do not acknowledge or properly implement TFTP options.
              When this option is used --tftp-blksize is ignored.

              Added in 7.48.0.

       -z, --time-cond <time>
              (HTTP FTP) Request a file that has been modified later
              than the given time and date, or one that has been
              modified before that time. The <date expression> can be
              all sorts of date strings or if it doesn't match any
              internal ones, it is taken as a filename and tries to get
              the modification date (mtime) from <file> instead. See the
              curl_getdate(3) man pages for date expression details.

              Start the date expression with a dash (-) to make it
              request for a document that is older than the given
              date/time, default is a document that is newer than the
              specified date/time.

              If this option is used several times, the last one will be
              used.

       --tls-max <VERSION>
              (SSL) VERSION defines maximum supported TLS version. The
              minimum acceptable version is set by tlsv1.0, tlsv1.1,
              tlsv1.2 or tlsv1.3.

              If the connection is done without TLS, this option has no
              effect. This includes QUIC-using (HTTP/3) transfers.

              default
                     Use up to recommended TLS version.

              1.0    Use up to TLSv1.0.

              1.1    Use up to TLSv1.1.

              1.2    Use up to TLSv1.2.

              1.3    Use up to TLSv1.3.

       See also --tlsv1.0, --tlsv1.1, --tlsv1.2 and --tlsv1.3. --tls-max
       requires that the underlying libcurl was built to support TLS.
       Added in 7.54.0.

       --tls13-ciphers <ciphersuite list>
              (TLS) Specifies which cipher suites to use in the
              connection if it negotiates TLS 1.3. The list of ciphers
              suites must specify valid ciphers. Read up on TLS 1.3
              cipher suite details on this URL:

               https://curl.se/docs/ssl-ciphers.html

              This option is currently used only when curl is built to
              use OpenSSL 1.1.1 or later. If you are using a different
              SSL backend you can try setting TLS 1.3 cipher suites by
              using the --ciphers option.

              If this option is used several times, the last one will be
              used.

       --tlsauthtype <type>
              Set TLS authentication type. Currently, the only supported
              option is "SRP", for TLS-SRP (RFC 5054). If --tlsuser and
              --tlspassword are specified but --tlsauthtype is not, then
              this option defaults to "SRP".  This option works only if
              the underlying libcurl is built with TLS-SRP support,
              which requires OpenSSL or GnuTLS with TLS-SRP support.

              Added in 7.21.4.

       --tlspassword
              Set password for use with the TLS authentication method
              specified with --tlsauthtype. Requires that --tlsuser also
              be set.

              This doesn't work with TLS 1.3.

              Added in 7.21.4.

       --tlsuser <name>
              Set username for use with the TLS authentication method
              specified with --tlsauthtype. Requires that --tlspassword
              also is set.

              This doesn't work with TLS 1.3.

              Added in 7.21.4.

       --tlsv1.0
              (TLS) Forces curl to use TLS version 1.0 or later when
              connecting to a remote TLS server.

              In old versions of curl this option was documented to
              allow _only_ TLS 1.0, but behavior was inconsistent
              depending on the TLS library. Use --tls-max if you want to
              set a maximum TLS version.

              Added in 7.34.0.

       --tlsv1.1
              (TLS) Forces curl to use TLS version 1.1 or later when
              connecting to a remote TLS server.

              In old versions of curl this option was documented to
              allow _only_ TLS 1.1, but behavior was inconsistent
              depending on the TLS library. Use --tls-max if you want to
              set a maximum TLS version.

              Added in 7.34.0.

       --tlsv1.2
              (TLS) Forces curl to use TLS version 1.2 or later when
              connecting to a remote TLS server.

              In old versions of curl this option was documented to
              allow _only_ TLS 1.2, but behavior was inconsistent
              depending on the TLS library. Use --tls-max if you want to
              set a maximum TLS version.

              Added in 7.34.0.

       --tlsv1.3
              (TLS) Forces curl to use TLS version 1.3 or later when
              connecting to a remote TLS server.

              If the connection is done without TLS, this option has no
              effect. This includes QUIC-using (HTTP/3) transfers.

              Note that TLS 1.3 is not supported by all TLS backends.

              Added in 7.52.0.

       -1, --tlsv1
              (SSL) Tells curl to use at least TLS version 1.x when
              negotiating with a remote TLS server. That means TLS
              version 1.0 or higher

              See also --http1.1 and --http2. -1, --tlsv1 requires that
              the underlying libcurl was built to support TLS. This
              option overrides --tlsv1.1 and --tlsv1.2 and --tlsv1.3.

       --tr-encoding
              (HTTP) Request a compressed Transfer-Encoding response
              using one of the algorithms curl supports, and uncompress
              the data while receiving it.

              Added in 7.21.6.

       --trace-ascii <file>
              Enables a full trace dump of all incoming and outgoing
              data, including descriptive information, to the given
              output file. Use "-" as filename to have the output sent
              to stdout.

              This is very similar to --trace, but leaves out the hex
              part and only shows the ASCII part of the dump. It makes
              smaller output that might be easier to read for untrained
              humans.

              If this option is used several times, the last one will be
              used.

              This option overrides --trace and -v, --verbose.

       --trace-time
              Prepends a time stamp to each trace or verbose line that
              curl displays.

              Added in 7.14.0.

       --trace <file>
              Enables a full trace dump of all incoming and outgoing
              data, including descriptive information, to the given
              output file. Use "-" as filename to have the output sent
              to stdout. Use "%" as filename to have the output sent to
              stderr.

              If this option is used several times, the last one will be
              used.

              This option overrides -v, --verbose and --trace-ascii.

       --unix-socket <path>
              (HTTP) Connect through this Unix domain socket, instead of
              using the network.

              Added in 7.40.0.

       -T, --upload-file <file>
              This transfers the specified local file to the remote URL.
              If there is no file part in the specified URL, curl will
              append the local file name. NOTE that you must use a
              trailing / on the last directory to really prove to Curl
              that there is no file name or curl will think that your
              last directory name is the remote file name to use. That
              will most likely cause the upload operation to fail. If
              this is used on an HTTP(S) server, the PUT command will be
              used.

              Use the file name "-" (a single dash) to use stdin instead
              of a given file.  Alternately, the file name "." (a single
              period) may be specified instead of "-" to use stdin in
              non-blocking mode to allow reading server output while
              stdin is being uploaded.

              You can specify one -T, --upload-file for each URL on the
              command line. Each -T, --upload-file + URL pair specifies
              what to upload and to where. curl also supports "globbing"
              of the -T, --upload-file argument, meaning that you can
              upload multiple files to a single URL by using the same
              URL globbing style supported in the URL, like this:

               curl --upload-file "{file1,file2}" http://www.example.com

              or even

               curl -T "img[1-1000].png" ftp://ftp.example.com/upload/

              When uploading to an SMTP server: the uploaded data is
              assumed to be RFC 5322 formatted. It has to feature the
              necessary set of headers and mail body formatted correctly
              by the user as curl will not transcode nor encode it
              further in any way.

       --url <url>
              Specify a URL to fetch. This option is mostly handy when
              you want to specify URL(s) in a config file.

              If the given URL is missing a scheme name (such as
              "http://" or "ftp://" etc) then curl will make a guess
              based on the host. If the outermost sub-domain name
              matches DICT, FTP, IMAP, LDAP, POP3 or SMTP then that
              protocol will be used, otherwise HTTP will be used. Since
              7.45.0 guessing can be disabled by setting a default
              protocol, see --proto-default for details.

              This option may be used any number of times. To control
              where this URL is written, use the -o, --output or the -O,
              --remote-name options.

              Warning: On Windows, particular file:// accesses can be
              converted to network accesses by the operating system.
              Beware!

       -B, --use-ascii
              (FTP LDAP) Enable ASCII transfer. For FTP, this can also
              be enforced by using a URL that ends with ";type=A". This
              option causes data sent to stdout to be in text mode for
              win32 systems.

       -A, --user-agent <name>
              (HTTP) Specify the User-Agent string to send to the HTTP
              server. To encode blanks in the string, surround the
              string with single quote marks. This header can also be
              set with the -H, --header or the --proxy-header options.

              If you give an empty argument to -A, --user-agent (""), it
              will remove the header completely from the request. If you
              prefer a blank header, you can set it to a single space ("
              ").

              If this option is used several times, the last one will be
              used.

       -u, --user <user:password>
              Specify the user name and password to use for server
              authentication. Overrides -n, --netrc and --netrc-
              optional.

              If you simply specify the user name, curl will prompt for
              a password.

              The user name and passwords are split up on the first
              colon, which makes it impossible to use a colon in the
              user name with this option. The password can, still.

              On systems where it works, curl will hide the given option
              argument from process listings. This is not enough to
              protect credentials from possibly getting seen by other
              users on the same system as they will still be visible for
              a brief moment before cleared. Such sensitive data should
              be retrieved from a file instead or similar and never used
              in clear text in a command line.

              When using Kerberos V5 with a Windows based server you
              should include the Windows domain name in the user name,
              in order for the server to successfully obtain a Kerberos
              Ticket. If you don't then the initial authentication
              handshake may fail.

              When using NTLM, the user name can be specified simply as
              the user name, without the domain, if there is a single
              domain and forest in your setup for example.

              To specify the domain name use either Down-Level Logon
              Name or UPN (User Principal Name) formats. For example,
              EXAMPLE\user and user@example.com respectively.

              If you use a Windows SSPI-enabled curl binary and perform
              Kerberos V5, Negotiate, NTLM or Digest authentication then
              you can tell curl to select the user name and password
              from your environment by specifying a single colon with
              this option: "-u :".

              If this option is used several times, the last one will be
              used.

       -v, --verbose
              Makes curl verbose during the operation. Useful for
              debugging and seeing what's going on "under the hood". A
              line starting with '>' means "header data" sent by curl,
              '<' means "header data" received by curl that is hidden in
              normal cases, and a line starting with '*' means
              additional info provided by curl.

              If you only want HTTP headers in the output, -i, --include
              might be the option you're looking for.

              If you think this option still doesn't give you enough
              details, consider using --trace or --trace-ascii instead.

              Use -s, --silent to make curl really quiet.

              See also -i, --include. This option overrides --trace and
              --trace-ascii.

       -V, --version
              Displays information about curl and the libcurl version it
              uses.

              The first line includes the full version of curl, libcurl
              and other 3rd party libraries linked with the executable.

              The second line (starts with "Protocols:") shows all
              protocols that libcurl reports to support.

              The third line (starts with "Features:") shows specific
              features libcurl reports to offer. Available features
              include:

              alt-svc
                     Support for the Alt-Svc: header is provided.

              AsynchDNS
                     This curl uses asynchronous name resolves.
                     Asynchronous name resolves can be done using either
                     the c-ares or the threaded resolver backends.

              brotli Support for automatic brotli compression over
                     HTTP(S).

              CharConv
                     curl was built with support for character set
                     conversions (like EBCDIC)

              Debug  This curl uses a libcurl built with Debug. This
                     enables more error-tracking and memory debugging
                     etc. For curl-developers only!

              gsasl  The built-in SASL authentication includes
                     extensions to support SCRAM because libcurl was
                     built with libgsasl.

              GSS-API
                     GSS-API is supported.

              HSTS   HSTS support is present.

              HTTP2  HTTP/2 support has been built-in.

              HTTP3  HTTP/3 support has been built-in.

              HTTPS-proxy
                     This curl is built to support HTTPS proxy.

              IDN    This curl supports IDN - international domain
                     names.

              IPv6   You can use IPv6 with this.

              Kerberos
                     Kerberos V5 authentication is supported.

              Largefile
                     This curl supports transfers of large files, files
                     larger than 2GB.

              libz   Automatic decompression (via gzip, deflate) of
                     compressed files over HTTP is supported.

              MultiSSL
                     This curl supports multiple TLS backends.

              NTLM   NTLM authentication is supported.

              NTLM_WB
                     NTLM delegation to winbind helper is supported.

              PSL    PSL is short for Public Suffix List and means that
                     this curl has been built with knowledge about
                     "public suffixes".

              SPNEGO SPNEGO authentication is supported.

              SSL    SSL versions of various protocols are supported,
                     such as HTTPS, FTPS, POP3S and so on.

              SSPI   SSPI is supported.

              TLS-SRP
                     SRP (Secure Remote Password) authentication is
                     supported for TLS.

              TrackMemory
                     Debug memory tracking is supported.

              Unicode
                     Unicode support on Windows.

              UnixSockets
                     Unix sockets support is provided.

              zstd   Automatic decompression (via zstd) of compressed
                     files over HTTP is supported.

       -w, --write-out <format>
              Make curl display information on stdout after a completed
              transfer. The format is a string that may contain plain
              text mixed with any number of variables. The format can be
              specified as a literal "string", or you can have curl read
              the format from a file with "@filename" and to tell curl
              to read the format from stdin you write "@-".

              The variables present in the output format will be
              substituted by the value or text that curl thinks fit, as
              described below. All variables are specified as
              %{variable_name} and to output a normal % you just write
              them as %%. You can output a newline by using \n, a
              carriage return with \r and a tab space with \t.

              The output will be written to standard output, but this
              can be switched to standard error by using %{stderr}.

              NOTE: The %-symbol is a special symbol in the
              win32-environment, where all occurrences of % must be
              doubled when using this option.

              The variables available are:

              content_type
                     The Content-Type of the requested document, if
                     there was any.

              errormsg
                     The error message. (Added in 7.75.0)

              exitcode
                     The numerical exitcode of the transfer. (Added in
                     7.75.0)

              filename_effective
                     The ultimate filename that curl writes out to. This
                     is only meaningful if curl is told to write to a
                     file with the -O, --remote-name or -o, --output
                     option. It's most useful in combination with the
                     -J, --remote-header-name option. (Added in 7.26.0)

              ftp_entry_path
                     The initial path curl ended up in when logging on
                     to the remote FTP server. (Added in 7.15.4)

              http_code
                     The numerical response code that was found in the
                     last retrieved HTTP(S) or FTP(s) transfer. In
                     7.18.2 the alias response_code was added to show
                     the same info.

              http_connect
                     The numerical code that was found in the last
                     response (from a proxy) to a curl CONNECT request.
                     (Added in 7.12.4)

              http_version
                     The http version that was effectively used. (Added
                     in 7.50.0)

              json   A JSON object with all available keys.

              local_ip
                     The IP address of the local end of the most
                     recently done connection - can be either IPv4 or
                     IPv6 (Added in 7.29.0)

              local_port
                     The local port number of the most recently done
                     connection (Added in 7.29.0)

              method The http method used in the most recent HTTP
                     request (Added in 7.72.0)

              num_connects
                     Number of new connects made in the recent transfer.
                     (Added in 7.12.3)

              num_headers
                     The number of response headers in the most recent
                     request (restarted at each
                      redirect). Note that the status line IS NOT a
                     header. (Added in 7.73.0)

              num_redirects
                     Number of redirects that were followed in the
                     request. (Added in 7.12.3)

              onerror
                     The rest of the output is only shown if the
                     transfer returned a non-zero error (Added in
                     7.75.0)

              proxy_ssl_verify_result
                     The result of the HTTPS proxy's SSL peer
                     certificate verification that was requested. 0
                     means the verification was successful. (Added in
                     7.52.0)

              redirect_url
                     When an HTTP request was made without -L,
                     --location to follow redirects (or when --max-
                     redirs is met), this variable will show the actual
                     URL a redirect would have gone to. (Added in
                     7.18.2)

              referer
                     The Referer: header, if there was any. (Added in
                     7.76.0)

              remote_ip
                     The remote IP address of the most recently done
                     connection - can be either IPv4 or IPv6 (Added in
                     7.29.0)

              remote_port
                     The remote port number of the most recently done
                     connection (Added in 7.29.0)

              response_code
                     The numerical response code that was found in the
                     last transfer (formerly known as "http_code").
                     (Added in 7.18.2)

              scheme The URL scheme (sometimes called protocol) that was
                     effectively used (Added in 7.52.0)

              size_download
                     The total amount of bytes that were downloaded.

              size_header
                     The total amount of bytes of the downloaded
                     headers.

              size_request
                     The total amount of bytes that were sent in the
                     HTTP request.

              size_upload
                     The total amount of bytes that were uploaded.

              speed_download
                     The average download speed that curl measured for
                     the complete download. Bytes per second.

              speed_upload
                     The average upload speed that curl measured for the
                     complete upload. Bytes per second.

              ssl_verify_result
                     The result of the SSL peer certificate verification
                     that was requested. 0 means the verification was
                     successful. (Added in 7.19.0)

              stderr From this point on, the -w, --write-out output will
                     be written to standard error. (Added in 7.63.0)

              stdout From this point on, the -w, --write-out output will
                     be written to standard output.  This is the
                     default, but can be used to switch back after
                     switching to stderr.  (Added in 7.63.0)

              time_appconnect
                     The time, in seconds, it took from the start until
                     the SSL/SSH/etc connect/handshake to the remote
                     host was completed. (Added in 7.19.0)

              time_connect
                     The time, in seconds, it took from the start until
                     the TCP connect to the remote host (or proxy) was
                     completed.

              time_namelookup
                     The time, in seconds, it took from the start until
                     the name resolving was completed.

              time_pretransfer
                     The time, in seconds, it took from the start until
                     the file transfer was just about to begin. This
                     includes all pre-transfer commands and negotiations
                     that are specific to the particular protocol(s)
                     involved.

              time_redirect
                     The time, in seconds, it took for all redirection
                     steps including name lookup, connect, pretransfer
                     and transfer before the final transaction was
                     started. time_redirect shows the complete execution
                     time for multiple redirections. (Added in 7.12.3)

              time_starttransfer
                     The time, in seconds, it took from the start until
                     the first byte was just about to be transferred.
                     This includes time_pretransfer and also the time
                     the server needed to calculate the result.

              time_total
                     The total time, in seconds, that the full operation
                     lasted.

              url    The URL that was fetched. (Added in 7.75.0)

              urlnum The URL index number of this transfer, 0-indexed.
                     (Added in 7.75.0)

              url_effective
                     The URL that was fetched last. This is most
                     meaningful if you've told curl to follow location:
                     headers.

              If this option is used several times, the last one will be
              used.

       --xattr
              When saving output to a file, this option tells curl to
              store certain file metadata in extended file attributes.
              Currently, the URL is stored in the xdg.origin.url
              attribute and, for HTTP, the content type is stored in the
              mime_type attribute. If the file system does not support
              extended attributes, a warning is issued.

FILES         top

       ~/.curlrc
              Default config file, see -K, --config for details.

ENVIRONMENT         top

       The environment variables can be specified in lower case or upper
       case. The lower case version has precedence. http_proxy is an
       exception as it is only available in lower case.

       Using an environment variable to set the proxy has the same
       effect as using the -x, --proxy option.

       http_proxy [protocol://]<host>[:port]
              Sets the proxy server to use for HTTP.

       HTTPS_PROXY [protocol://]<host>[:port]
              Sets the proxy server to use for HTTPS.

       [url-protocol]_PROXY [protocol://]<host>[:port]
              Sets the proxy server to use for [url-protocol], where the
              protocol is a protocol that curl supports and as specified
              in a URL. FTP, FTPS, POP3, IMAP, SMTP, LDAP etc.

       ALL_PROXY [protocol://]<host>[:port]
              Sets the proxy server to use if no protocol-specific proxy
              is set.

       NO_PROXY <comma-separated list of hosts/domains>
              list of host names that shouldn't go through any proxy. If
              set to an asterisk '*' only, it matches all hosts. Each
              name in this list is matched as either a domain name which
              contains the hostname, or the hostname itself.

              This environment variable disables use of the proxy even
              when specified with the -x, --proxy option. That is
              NO_PROXY=direct.example.com curl -x
              http://proxy.example.com http://direct.example.com
              accesses the target URL directly, and
              NO_PROXY=direct.example.com curl -x
              http://proxy.example.com http://somewhere.example.com
              accesses the target URL through the proxy.

              The list of host names can also be include numerical IP
              addresses, and IPv6 versions should then be given without
              enclosing brackets.

              IPv6 numerical addresses are compared as strings, so they
              will only match if the representations are the same: "::1"
              is the same as "::0:1" but they don't match.

       CURL_SSL_BACKEND <TLS backend>
              If curl was built with support for "MultiSSL", meaning
              that it has built-in support for more than one TLS
              backend, this environment variable can be set to the case
              insensitive name of the particular backend to use when
              curl is invoked. Setting a name that isn't a built-in
              alternative will make curl stay with the default.

              SSL backend names (case-insensitive): bearssl, gnutls,
              gskit, mbedtls, mesalink, nss, openssl, rustls, schannel,
              secure-transport, wolfssl

       QLOGDIR <directory name>
              If curl was built with HTTP/3 support, setting this
              environment variable to a local directory will make curl
              produce qlogs in that directory, using file names named
              after the destination connection id (in hex). Do note that
              these files can become rather large. Works with both QUIC
              backends.

       SSLKEYLOGFILE <file name>
              If you set this environment variable to a file name, curl
              will store TLS secrets from its connections in that file
              when invoked to enable you to analyze the TLS traffic in
              real time using network analyzing tools such as Wireshark.
              This works with the following TLS backends: OpenSSL,
              libressl, BoringSSL, GnuTLS, NSS and wolfSSL.

PROXY PROTOCOL PREFIXES         top

       Since curl version 7.21.7, the proxy string may be specified with
       a protocol:// prefix to specify alternative proxy protocols.

       If no protocol is specified in the proxy string or if the string
       doesn't match a supported one, the proxy will be treated as an
       HTTP proxy.

       The supported proxy protocol prefixes are as follows:

       http://
              Makes it use it as an HTTP proxy. The default if no scheme
              prefix is used.

       https://
              Makes it treated as an HTTPS proxy.

       socks4://
              Makes it the equivalent of --socks4

       socks4a://
              Makes it the equivalent of --socks4a

       socks5://
              Makes it the equivalent of --socks5

       socks5h://
              Makes it the equivalent of --socks5-hostname

EXIT CODES         top

       There are a bunch of different error codes and their
       corresponding error messages that may appear during bad
       conditions. At the time of this writing, the exit codes are:

       1      Unsupported protocol. This build of curl has no support
              for this protocol.

       2      Failed to initialize.

       3      URL malformed. The syntax was not correct.

       4      A feature or option that was needed to perform the desired
              request was not enabled or was explicitly disabled at
              build-time. To make curl able to do this, you probably
              need another build of libcurl!

       5      Couldn't resolve proxy. The given proxy host could not be
              resolved.

       6      Couldn't resolve host. The given remote host was not
              resolved.

       7      Failed to connect to host.

       8      Weird server reply. The server sent data curl couldn't
              parse.

       9      FTP access denied. The server denied login or denied
              access to the particular resource or directory you wanted
              to reach. Most often you tried to change to a directory
              that doesn't exist on the server.

       10     FTP accept failed. While waiting for the server to connect
              back when an active FTP session is used, an error code was
              sent over the control connection or similar.

       11     FTP weird PASS reply. Curl couldn't parse the reply sent
              to the PASS request.

       12     During an active FTP session while waiting for the server
              to connect back to curl, the timeout expired.

       13     FTP weird PASV reply, Curl couldn't parse the reply sent
              to the PASV request.

       14     FTP weird 227 format. Curl couldn't parse the 227-line the
              server sent.

       15     FTP can't get host. Couldn't resolve the host IP we got in
              the 227-line.

       16     HTTP/2 error. A problem was detected in the HTTP2 framing
              layer. This is somewhat generic and can be one out of
              several problems, see the error message for details.

       17     FTP couldn't set binary. Couldn't change transfer method
              to binary.

       18     Partial file. Only a part of the file was transferred.

       19     FTP couldn't download/access the given file, the RETR (or
              similar) command failed.

       21     FTP quote error. A quote command returned error from the
              server.

       22     HTTP page not retrieved. The requested url was not found
              or returned another error with the HTTP error code being
              400 or above. This return code only appears if -f, --fail
              is used.

       23     Write error. Curl couldn't write data to a local
              filesystem or similar.

       25     FTP couldn't STOR file. The server denied the STOR
              operation, used for FTP uploading.

       26     Read error. Various reading problems.

       27     Out of memory. A memory allocation request failed.

       28     Operation timeout. The specified time-out period was
              reached according to the conditions.

       30     FTP PORT failed. The PORT command failed. Not all FTP
              servers support the PORT command, try doing a transfer
              using PASV instead!

       31     FTP couldn't use REST. The REST command failed. This
              command is used for resumed FTP transfers.

       33     HTTP range error. The range "command" didn't work.

       34     HTTP post error. Internal post-request generation error.

       35     SSL connect error. The SSL handshaking failed.

       36     Bad download resume. Couldn't continue an earlier aborted
              download.

       37     FILE couldn't read file. Failed to open the file.
              Permissions?

       38     LDAP cannot bind. LDAP bind operation failed.

       39     LDAP search failed.

       41     Function not found. A required LDAP function was not
              found.

       42     Aborted by callback. An application told curl to abort the
              operation.

       43     Internal error. A function was called with a bad
              parameter.

       45     Interface error. A specified outgoing interface could not
              be used.

       47     Too many redirects. When following redirects, curl hit the
              maximum amount.

       48     Unknown option specified to libcurl. This indicates that
              you passed a weird option to curl that was passed on to
              libcurl and rejected. Read up in the manual!

       49     Malformed telnet option.

       51     The peer's SSL certificate or SSH MD5 fingerprint was not
              OK.

       52     The server didn't reply anything, which here is considered
              an error.

       53     SSL crypto engine not found.

       54     Cannot set SSL crypto engine as default.

       55     Failed sending network data.

       56     Failure in receiving network data.

       58     Problem with the local certificate.

       59     Couldn't use specified SSL cipher.

       60     Peer certificate cannot be authenticated with known CA
              certificates.

       61     Unrecognized transfer encoding.

       62     Invalid LDAP URL.

       63     Maximum file size exceeded.

       64     Requested FTP SSL level failed.

       65     Sending the data requires a rewind that failed.

       66     Failed to initialise SSL Engine.

       67     The user name, password, or similar was not accepted and
              curl failed to log in.

       68     File not found on TFTP server.

       69     Permission problem on TFTP server.

       70     Out of disk space on TFTP server.

       71     Illegal TFTP operation.

       72     Unknown TFTP transfer ID.

       73     File already exists (TFTP).

       74     No such user (TFTP).

       75     Character conversion failed.

       76     Character conversion functions required.

       77     Problem with reading the SSL CA cert (path? access
              rights?).

       78     The resource referenced in the URL does not exist.

       79     An unspecified error occurred during the SSH session.

       80     Failed to shut down the SSL connection.

       82     Could not load CRL file, missing or wrong format (added in
              7.19.0).

       83     Issuer check failed (added in 7.19.0).

       84     The FTP PRET command failed

       85     RTSP: mismatch of CSeq numbers

       86     RTSP: mismatch of Session Identifiers

       87     unable to parse FTP file list

       88     FTP chunk callback reported error

       89     No connection available, the session will be queued

       90     SSL public key does not matched pinned public key

       91     Invalid SSL certificate status.

       92     Stream error in HTTP/2 framing layer.

       93     An API function was called from inside a callback.

       94     An authentication function returned an error.

       95     A problem was detected in the HTTP/3 layer. This is
              somewhat generic and can be one out of several problems,
              see the error message for details.

       96     QUIC connection error. This error may be caused by an SSL
              library error. QUIC is the protocol used for HTTP/3
              transfers.

       XX     More error codes will appear here in future releases. The
              existing ones are meant to never change.

AUTHORS / CONTRIBUTORS         top

       Daniel Stenberg is the main author, but the whole list of
       contributors is found in the separate THANKS file.

WWW         top

       https://curl.se

SEE ALSO         top

       ftp(1), wget(1)

COLOPHON         top

       This page is part of the curl (Command line tool and library for
       transferring data with URLs) project.  Information about the
       project can be found at ⟨https://curl.haxx.se/⟩.  If you have a
       bug report for this manual page, see
       ⟨https://curl.haxx.se/docs/bugs.html⟩.  This page was obtained
       from the project's upstream Git repository
       ⟨https://github.com/curl/curl.git⟩ on 2021-06-20.  (At that time,
       the date of the most recent commit that was found in the
       repository was 2021-06-19.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

Curl 7.52.0                    16 Dec 2016                       curl(1)

Pages that refer to this page: curl-config(1)git-config(1)mk-ca-bundle(1)pmwebapi(3)systemd-socket-proxyd(8)