visudo(8) — Linux manual page

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

VISUDO(8)              BSD 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.

     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 submit a bug
     report at https://bugzilla.sudo.ws/

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 2023-06-23.  (At that
     time, the date of the most recent commit that was found in the
     repository was 2023-06-21.)  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 1.9.14                  March 20, 2023                  Sudo 1.9.14