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 [-chqsV] [[-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 and no one
     will be able to run sudo again until the error is fixed.  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.  Note that 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 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.  Note that 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 int 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 owner and
                 mode.  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.

     -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.  Note that 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, UID,
     GID 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=uid
               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=gid
               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), please 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.

     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 file in the sudo distribution
     (https://www.sudo.ws/contributors.html) 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 feel you have found a bug in visudo, please 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 file distributed with sudo or
     https://www.sudo.ws/license.html 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 2021-04-01.  (At that
     time, the date of the most recent commit that was found in the
     repository was 2021-03-31.)  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 1.9.6p1                 August 27, 2020                Sudo 1.9.6p1