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

visudo - edit the sudoers file

visudo [-chIOPqsV] [[-f] sudoers]

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.

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.
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:

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.
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.
Display a short help message to the standard output and exit.
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.
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.
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.
Enable quiet mode. In this mode details about syntax errors are not printed. This option is only useful when combined with the -c option.
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.
Print the visudo and sudoers grammar versions and exit.

A sudoers file may be specified instead of the default, /private/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.

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:



  

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

  

  
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.

  

  
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).

  

  
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.










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



  

  
Invoked by visudo as the editor to use

  

  
Used by visudo if SUDO_EDITOR is not set

  

  
Used by visudo if neither SUDO_EDITOR nor VISUAL is set











  
/private/etc/sudo.conf

  
Sudo front-end configuration

  
/private/etc/sudoers

  
List of who can run what

  
/private/etc/sudoers.tmp

  
Default temporary file used by visudo










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



  

  
Someone else is currently editing the sudoers file.

  
/private/etc/sudoers: Permission denied

  
You didn't run visudo as root.

  

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

  

  
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.

  

  
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.

  

  
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.

  

  
The sudoers file contains a Defaults setting not recognized
      by visudo.










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








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.








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








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








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.








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.







  

    January 16, 2023
    Sudo 1.9.13p2