NAME | SYNOPSIS | DESCRIPTION | OPTIONS | PARSING | OUTPUT | QUOTING | SCANNING MODES | COMPATIBILITY | RETURN CODES | EXAMPLES | ENVIRONMENT | BUGS | AUTHOR | SEE ALSO | AVAILABILITY | COLOPHON

GETOPT(1)                       User Commands                      GETOPT(1)

NAME         top

       getopt - parse command options (enhanced)

SYNOPSIS         top

       getopt optstring parameters
       getopt [options] [--] optstring parameters
       getopt [options] -o|--options optstring [options] [--] parameters

DESCRIPTION         top

       getopt is used to break up (parse) options in command lines for easy
       parsing by shell procedures, and to check for legal options.  It uses
       the GNU getopt(3) routines to do this.

       The parameters getopt is called with can be divided into two parts:
       options which modify the way getopt will do the parsing (the options
       and the optstring in the SYNOPSIS), and the parameters which are to
       be parsed (parameters in the SYNOPSIS).  The second part will start
       at the first non-option parameter that is not an option argument, or
       after the first occurrence of '--'.  If no '-o' or '--options' option
       is found in the first part, the first parameter of the second part is
       used as the short options string.

       If the environment variable GETOPT_COMPATIBLE is set, or if the first
       parameter is not an option (does not start with a '-', the first
       format in the SYNOPSIS), getopt will generate output that is
       compatible with that of other versions of getopt(1).  It will still
       do parameter shuffling and recognize optional arguments (see section
       COMPATIBILITY for more information).

       Traditional implementations of getopt(1) are unable to cope with
       whitespace and other (shell-specific) special characters in arguments
       and non-option parameters.  To solve this problem, this
       implementation can generate quoted output which must once again be
       interpreted by the shell (usually by using the eval command).  This
       has the effect of preserving those characters, but you must call
       getopt in a way that is no longer compatible with other versions (the
       second or third format in the SYNOPSIS).  To determine whether this
       enhanced version of getopt(1) is installed, a special test option
       (-T) can be used.

OPTIONS         top

       -a, --alternative
              Allow long options to start with a single '-'.

       -h, --help
              Display help text and exit.  No other output is generated.

       -l, --longoptions longopts
              The long (multi-character) options to be recognized.  More
              than one option name may be specified at once, by separating
              the names with commas.  This option may be given more than
              once, the longopts are cumulative.  Each long option name in
              longopts may be followed by one colon to indicate it has a
              required argument, and by two colons to indicate it has an
              optional argument.

       -n, --name progname
              The name that will be used by the getopt(3) routines when it
              reports errors.  Note that errors of getopt(1) are still
              reported as coming from getopt.

       -o, --options shortopts
              The short (one-character) options to be recognized.  If this
              option is not found, the first parameter of getopt that does
              not start with a '-' (and is not an option argument) is used
              as the short options string.  Each short option character in
              shortopts may be followed by one colon to indicate it has a
              required argument, and by two colons to indicate it has an
              optional argument.  The first character of shortopts may be
              '+' or '-' to influence the way options are parsed and output
              is generated (see section SCANNING MODES for details).

       -q, --quiet
              Disable error reporting by getopt(3).

       -Q, --quiet-output
              Do not generate normal output.  Errors are still reported by
              getopt(3), unless you also use -q.

       -s, --shell shell
              Set quoting conventions to those of shell.  If the -s option
              is not given, the BASH conventions are used.  Valid arguments
              are currently 'sh' 'bash', 'csh', and 'tcsh'.

       -T, --test
              Test if your getopt(1) is this enhanced version or an old
              version.  This generates no output, and sets the error status
              to 4.  Other implementations of getopt(1), and this version if
              the environment variable GETOPT_COMPATIBLE is set, will return
              '--' and error status 0.

       -u, --unquoted
              Do not quote the output.  Note that whitespace and special
              (shell-dependent) characters can cause havoc in this mode
              (like they do with other getopt(1) implementations).

       -V, --version
              Display version information and exit.  No other output is
              generated.

PARSING         top

       This section specifies the format of the second part of the
       parameters of getopt (the parameters in the SYNOPSIS).  The next
       section (OUTPUT) describes the output that is generated.  These
       parameters were typically the parameters a shell function was called
       with.  Care must be taken that each parameter the shell function was
       called with corresponds to exactly one parameter in the parameter
       list of getopt (see the EXAMPLES).  All parsing is done by the GNU
       getopt(3) routines.

       The parameters are parsed from left to right.  Each parameter is
       classified as a short option, a long option, an argument to an
       option, or a non-option parameter.

       A simple short option is a '-' followed by a short option character.
       If the option has a required argument, it may be written directly
       after the option character or as the next parameter (i.e. separated
       by whitespace on the command line).  If the option has an optional
       argument, it must be written directly after the option character if
       present.

       It is possible to specify several short options after one '-', as
       long as all (except possibly the last) do not have required or
       optional arguments.

       A long option normally begins with '--' followed by the long option
       name.  If the option has a required argument, it may be written
       directly after the long option name, separated by '=', or as the next
       argument (i.e. separated by whitespace on the command line).  If the
       option has an optional argument, it must be written directly after
       the long option name, separated by '=', if present (if you add the
       '=' but nothing behind it, it is interpreted as if no argument was
       present; this is a slight bug, see the BUGS).  Long options may be
       abbreviated, as long as the abbreviation is not ambiguous.

       Each parameter not starting with a '-', and not a required argument
       of a previous option, is a non-option parameter.  Each parameter
       after a '--' parameter is always interpreted as a non-option
       parameter.  If the environment variable POSIXLY_CORRECT is set, or if
       the short option string started with a '+', all remaining parameters
       are interpreted as non-option parameters as soon as the first
       non-option parameter is found.

OUTPUT         top

       Output is generated for each element described in the previous
       section.  Output is done in the same order as the elements are
       specified in the input, except for non-option parameters.  Output can
       be done in compatible (unquoted) mode, or in such way that whitespace
       and other special characters within arguments and non-option
       parameters are preserved (see QUOTING).  When the output is processed
       in the shell script, it will seem to be composed of distinct elements
       that can be processed one by one (by using the shift command in most
       shell languages).  This is imperfect in unquoted mode, as elements
       can be split at unexpected places if they contain whitespace or
       special characters.

       If there are problems parsing the parameters, for example because a
       required argument is not found or an option is not recognized, an
       error will be reported on stderr, there will be no output for the
       offending element, and a non-zero error status is returned.

       For a short option, a single '-' and the option character are
       generated as one parameter.  If the option has an argument, the next
       parameter will be the argument.  If the option takes an optional
       argument, but none was found, the next parameter will be generated
       but be empty in quoting mode, but no second parameter will be
       generated in unquoted (compatible) mode.  Note that many other
       getopt(1) implementations do not support optional arguments.

       If several short options were specified after a single '-', each will
       be present in the output as a separate parameter.

       For a long option, '--' and the full option name are generated as one
       parameter.  This is done regardless whether the option was
       abbreviated or specified with a single '-' in the input.  Arguments
       are handled as with short options.

       Normally, no non-option parameters output is generated until all
       options and their arguments have been generated.  Then '--' is
       generated as a single parameter, and after it the non-option
       parameters in the order they were found, each as a separate
       parameter.  Only if the first character of the short options string
       was a '-', non-option parameter output is generated at the place they
       are found in the input (this is not supported if the first format of
       the SYNOPSIS is used; in that case all preceding occurrences of '-'
       and '+' are ignored).

QUOTING         top

       In compatible mode, whitespace or 'special' characters in arguments
       or non-option parameters are not handled correctly.  As the output is
       fed to the shell script, the script does not know how it is supposed
       to break the output into separate parameters.  To circumvent this
       problem, this implementation offers quoting.  The idea is that output
       is generated with quotes around each parameter.  When this output is
       once again fed to the shell (usually by a shell eval command), it is
       split correctly into separate parameters.

       Quoting is not enabled if the environment variable GETOPT_COMPATIBLE
       is set, if the first form of the SYNOPSIS is used, or if the option
       '-u' is found.

       Different shells use different quoting conventions.  You can use the
       '-s' option to select the shell you are using.  The following shells
       are currently supported: 'sh', 'bash', 'csh' and 'tcsh'.  Actually,
       only two 'flavors' are distinguished: sh-like quoting conventions and
       csh-like quoting conventions.  Chances are that if you use another
       shell script language, one of these flavors can still be used.

SCANNING MODES         top

       The first character of the short options string may be a '-' or a '+'
       to indicate a special scanning mode.  If the first calling form in
       the SYNOPSIS is used they are ignored; the environment variable
       POSIXLY_CORRECT is still examined, though.

       If the first character is '+', or if the environment variable
       POSIXLY_CORRECT is set, parsing stops as soon as the first non-option
       parameter (i.e. a parameter that does not start with a '-') is found
       that is not an option argument.  The remaining parameters are all
       interpreted as non-option parameters.

       If the first character is a '-', non-option parameters are outputted
       at the place where they are found; in normal operation, they are all
       collected at the end of output after a '--' parameter has been
       generated.  Note that this '--' parameter is still generated, but it
       will always be the last parameter in this mode.

COMPATIBILITY         top

       This version of getopt(1) is written to be as compatible as possible
       to other versions.  Usually you can just replace them with this
       version without any modifications, and with some advantages.

       If the first character of the first parameter of getopt is not a '-',
       getopt goes into compatibility mode.  It will interpret its first
       parameter as the string of short options, and all other arguments
       will be parsed.  It will still do parameter shuffling (i.e. all
       non-option parameters are output at the end), unless the environment
       variable POSIXLY_CORRECT is set.

       The environment variable GETOPT_COMPATIBLE forces getopt into
       compatibility mode.  Setting both this environment variable and
       POSIXLY_CORRECT offers 100% compatibility for 'difficult' programs.
       Usually, though, neither is needed.

       In compatibility mode, leading '-' and '+' characters in the short
       options string are ignored.

RETURN CODES         top

       getopt returns error code 0 for successful parsing, 1 if getopt(3)
       returns errors, 2 if it does not understand its own parameters, 3 if
       an internal error occurs like out-of-memory, and 4 if it is called
       with -T.

EXAMPLES         top

       Example scripts for (ba)sh and (t)csh are provided with the getopt(1)
       distribution, and are optionally installed in /usr/share/getopt/ or
       /usr/share/doc/ in the util-linux subdirectory.

ENVIRONMENT         top

       POSIXLY_CORRECT
              This environment variable is examined by the getopt(3)
              routines.  If it is set, parsing stops as soon as a parameter
              is found that is not an option or an option argument.  All
              remaining parameters are also interpreted as non-option
              parameters, regardless whether they start with a '-'.

       GETOPT_COMPATIBLE
              Forces getopt to use the first calling format as specified in
              the SYNOPSIS.

BUGS         top

       getopt(3) can parse long options with optional arguments that are
       given an empty optional argument (but cannot do this for short
       options).  This getopt(1) treats optional arguments that are empty as
       if they were not present.

       The syntax if you do not want any short option variables at all is
       not very intuitive (you have to set them explicitly to the empty
       string).

AUTHOR         top

       Frodo Looijaard ⟨frodo@frodo.looijaard.name⟩

SEE ALSO         top

       bash(1), tcsh(1), getopt(3)

AVAILABILITY         top

       The getopt command is part of the util-linux package and is available
       from Linux Kernel Archive 
       ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩.

COLOPHON         top

       This page is part of the util-linux (a random collection of Linux
       utilities) project.  Information about the project can be found at 
       ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩.  If you have a
       bug report for this manual page, send it to
       util-linux@vger.kernel.org.  This page was obtained from the
       project's upstream Git repository 
       ⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on
       2017-04-25.  If you discover any rendering problems in this HTML ver‐
       sion 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 man‐
       ual page), send a mail to man-pages@man7.org

util-linux                      December 2014                      GETOPT(1)

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