visudo(8) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | ENVIRONMENT | FILES | DIAGNOSTICS | SEE ALSO | AUTHORS | CAVEATS | BUGS | SUPPORT | DISCLAIMER | COLOPHON

VISUDO(8)                System Manager's Manual               VISUDO(8)

NAME         top

       visudo — edit the sudoers file

SYNOPSIS         top

       visudo [-chIOPqsV] [[-f] sudoers]

DESCRIPTION         top

       visudo edits the sudoers file in a safe fashion, analogous to
       vipw(8).  visudo locks the sudoers file against multiple
       simultaneous edits, performs basic validity checks, and checks
       for syntax errors before installing the edited file.  If the
       sudoers file is currently being edited you will receive a message
       to try again later.

       If the sudoers file does not exist, it will be created unless the
       editor exits without writing to the file.

       visudo parses the sudoers file after editing and will not save
       the changes if there is a syntax error.  Upon finding an error,
       visudo will print a message stating the line number(s) where the
       error occurred and the user will receive the “What now?” prompt.
       At this point the user may enter ‘e’ to re-edit the sudoers file,
       ‘x’ to exit without saving the changes, or ‘Q’ to quit and save
       changes.  The ‘Q’ option should be used with extreme caution
       because if visudo believes there to be a syntax error, so will
       sudo.  If ‘e’ is typed to edit the sudoers file after a syntax
       error has been detected, the cursor will be placed on the line
       where the error occurred (if the editor supports this feature).

       There are two sudoers settings that determine which editor visudo
       will run.

       editor      A colon (‘:’) separated list of editors allowed to be
                   used with visudo.  visudo will choose the editor that
                   matches the user's SUDO_EDITOR, VISUAL, or EDITOR
                   environment variable if possible, or the first editor
                   in the list that exists and is executable.  sudo does
                   not preserve the SUDO_EDITOR, VISUAL, or EDITOR
                   environment variables unless they are present in the
                   env_keep list or the env_reset option is disabled in
                   the sudoers file.  The default editor path is
                   /usr/bin/vi which can be set at compile time via the
                   --with-editor configure option.

       env_editor  If set, visudo will use the value of the SUDO_EDITOR,
                   VISUAL, or EDITOR environment variables before
                   falling back on the default editor list.  visudo is
                   typically run as root so this option may allow a user
                   with visudo privileges to run arbitrary commands as
                   root without logging.  An alternative is to place a
                   colon-separated list of “safe” editors in the editor
                   variable.  visudo will then only use SUDO_EDITOR,
                   VISUAL, or EDITOR if they match a value specified in
                   editor.  If the env_reset flag is enabled, the
                   SUDO_EDITOR, VISUAL, and/or EDITOR environment
                   variables must be present in the env_keep list for
                   the env_editor flag to function when visudo is
                   invoked via sudo.  The default value is on, which can
                   be set at compile time via the --with-env-editor
                   configure option.

       The options are as follows:

       -c, --check
               Enable check-only mode.  The existing sudoers file (and
               any other files it includes) will be checked for syntax
               errors.  If the path to the sudoers file was not
               specified, visudo will also check the file ownership and
               permissions (see the -O and -P options).  A message will
               be printed to the standard output describing the status
               of sudoers unless the -q option was specified.  If the
               check completes successfully, visudo will exit with a
               value of 0.  If an error is encountered, visudo will exit
               with a value of 1.

       -f sudoers, --file=sudoers
               Specify an alternate sudoers file location, see below.
               As of version 1.8.27, the sudoers path can be specified
               without using the -f option.

       -h, --help
               Display a short help message to the standard output and
               exit.

       -I, --no-includes
               Disable the editing of include files unless there is a
               pre-existing syntax error.  By default, visudo will edit
               the main sudoers file and any files included via @include
               or #include directives.  Files included via @includedir
               or #includedir are never edited unless they contain a
               syntax error.

       -O, --owner
               Enforce the default ownership (user and group) of the
               sudoers file.  In edit mode, the owner of the edited file
               will be set to the default.  In check mode (-c), an error
               will be reported if the owner is incorrect.  This option
               is enabled by default if the sudoers file was not
               specified.

       -P, --perms
               Enforce the default permissions (mode) of the sudoers
               file.  In edit mode, the permissions of the edited file
               will be set to the default.  In check mode (-c), an error
               will be reported if the file permissions are incorrect.
               This option is enabled by default if the sudoers file was
               not specified.

       -q, --quiet
               Enable quiet mode.  In this mode details about syntax
               errors are not printed.  This option is only useful when
               combined with the -c option.

       -s, --strict
               Enable strict checking of the sudoers file.  If an alias
               is referenced but not actually defined or if there is a
               cycle in an alias, visudo will consider this a syntax
               error.  It is not possible to differentiate between an
               alias and a host name or user name that consists solely
               of uppercase letters, digits, and the underscore (‘_’)
               character.

       -V, --version
               Print the visudo and sudoers grammar versions and exit.

       A sudoers file may be specified instead of the default,
       /etc/sudoers.  The temporary file used is the specified sudoers
       file with “.tmp” appended to it.  In check-only mode only, ‘-’
       may be used to indicate that sudoers will be read from the
       standard input.  Because the policy is evaluated in its entirety,
       it is not sufficient to check an individual sudoers include file
       for syntax errors.

   Debugging and sudoers plugin arguments
       visudo versions 1.8.4 and higher support a flexible debugging
       framework that is configured via Debug lines in the sudo.conf(5)
       file.

       Starting with sudo 1.8.12, visudo will also parse the arguments
       to the sudoers plugin to override the default sudoers path name,
       user-ID, group-ID, and file mode.  These arguments, if present,
       should be listed after the path to the plugin (i.e., after
       sudoers.so).  Multiple arguments may be specified, separated by
       white space.  For example:

           Plugin sudoers_policy sudoers.so sudoers_mode=0400

       The following arguments are supported:

       sudoers_file=pathname
             The sudoers_file argument can be used to override the
             default path to the sudoers file.

       sudoers_uid=user-ID
             The sudoers_uid argument can be used to override the
             default owner of the sudoers file.  It should be specified
             as a numeric user-ID.

       sudoers_gid=group-ID
             The sudoers_gid argument can be used to override the
             default group of the sudoers file.  It must be specified as
             a numeric group-ID (not a group name).

       sudoers_mode=mode
             The sudoers_mode argument can be used to override the
             default file mode for the sudoers file.  It should be
             specified as an octal value.

       For more information on configuring sudo.conf(5), refer to its
       manual.

ENVIRONMENT         top

       The following environment variables may be consulted depending on
       the value of the editor and env_editor sudoers settings:

       SUDO_EDITOR      Invoked by visudo as the editor to use

       VISUAL           Used by visudo if SUDO_EDITOR is not set

       EDITOR           Used by visudo if neither SUDO_EDITOR nor VISUAL
                        is set

FILES         top

       /etc/sudo.conf            Sudo front-end configuration

       /etc/sudoers              List of who can run what

       /etc/sudoers.tmp          Default temporary file used by visudo

DIAGNOSTICS         top

       In addition to reporting sudoers syntax errors, visudo may
       produce the following messages:

       sudoers file busy, try again later.
             Someone else is currently editing the sudoers file.

       /etc/sudoers: Permission denied
             You didn't run visudo as root.

       you do not exist in the passwd database
             Your user-ID does not appear in the system passwd database.

       Warning: {User,Runas,Host,Cmnd}_Alias referenced but not defined
             Either you are trying to use an undeclared
             {User,Runas,Host,Cmnd}_Alias or you have a user or host
             name listed that consists solely of uppercase letters,
             digits, and the underscore (‘_’) character.  In the latter
             case, you can ignore the warnings (sudo will not complain).
             The message is prefixed with the path name of the sudoers
             file and the line number where the undefined alias was
             used.  In -s (strict) mode these are errors, not warnings.

       Warning: unused {User,Runas,Host,Cmnd}_Alias
             The specified {User,Runas,Host,Cmnd}_Alias was defined but
             never used.  The message is prefixed with the path name of
             the sudoers file and the line number where the unused alias
             was defined.  You may wish to comment out or remove the
             unused alias.

       Warning: cycle in {User,Runas,Host,Cmnd}_Alias
             The specified {User,Runas,Host,Cmnd}_Alias includes a
             reference to itself, either directly or through an alias it
             includes.  The message is prefixed with the path name of
             the sudoers file and the line number where the cycle was
             detected.  This is only a warning unless visudo is run in
             -s (strict) mode as sudo will ignore cycles when parsing
             the sudoers file.

       ignoring editor backup file
             While processing a @includedir or #includedir, a file was
             found with a name that ends in ‘~’ or .bak.  Such files are
             skipped by sudo and visudo.

       ignoring file name containing '.'
             While processing a @includedir or #includedir, a file was
             found with a name that contains a ‘.’ character.  Such
             files are skipped by sudo and visudo.

       unknown defaults entry "name"
             The sudoers file contains a Defaults setting not recognized
             by visudo.

SEE ALSO         top

       vi(1), sudo.conf(5), sudoers(5), sudo(8), vipw(8)

AUTHORS         top

       Many people have worked on sudo over the years; this version
       consists of code written primarily by:

             Todd C. Miller

       See the CONTRIBUTORS.md file in the sudo distribution
       (https://www.sudo.ws/about/contributors/) for an exhaustive list
       of people who have contributed to sudo.

CAVEATS         top

       There is no easy way to prevent a user from gaining a root shell
       if the editor used by visudo allows shell escapes.

BUGS         top

       If you believe you have found a bug in visudo, you can either
       file a bug report in the sudo bug database,
       https://bugzilla.sudo.ws/, or open an issue at
       https://github.com/sudo-project/sudo/issues.  If you would prefer
       to use email, messages may be sent to the sudo-workers mailing
       list, https://www.sudo.ws/mailman/listinfo/sudo-workers (public)
       or <sudo@sudo.ws> (private).

       Please not report security vulnerabilities through public GitHub
       issues, Bugzilla or mailing lists.  Instead, report them via
       email to <Todd.Miller@sudo.ws>.  You may encrypt your message
       with PGP if you would like, using the key found at
       https://www.sudo.ws/dist/PGPKEYS.

SUPPORT         top

       Limited free support is available via the sudo-users mailing
       list, see https://www.sudo.ws/mailman/listinfo/sudo-users to
       subscribe or search the archives.

DISCLAIMER         top

       visudo is provided “AS IS” and any express or implied warranties,
       including, but not limited to, the implied warranties of
       merchantability and fitness for a particular purpose are
       disclaimed.  See the LICENSE.md file distributed with sudo or
       https://www.sudo.ws/about/license/ for complete details.

COLOPHON         top

       This page is part of the sudo (execute a command as another user)
       project.  Information about the project can be found at
       https://www.sudo.ws/.  If you have a bug report for this manual
       page, see ⟨https://bugzilla.sudo.ws/⟩.  This page was obtained
       from the project's upstream Git repository
       ⟨https://github.com/sudo-project/sudo⟩ on 2024-06-14.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2024-06-08.)  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

Sudo 1.9.16                   July 27, 2023                    VISUDO(8)