NAME

     visudo — edit the sudoers file

SYNOPSIS

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

DESCRIPTION

     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/editor 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

     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

     /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

     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

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

AUTHORS

     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

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

BUGS

     If you believe you have found a bug in visudo, you can submit a bug report at https://bugzilla.sudo.ws/

SUPPORT

     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

     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.