Manual: visudo.ws

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

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 multi‐
       ple 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 ed‐
		   itor	 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 dis‐
		   abled 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 syn‐
	       tax 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 speci‐
	       fied 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 incor‐
	       rect.  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	 be‐
	       tween an alias and a host name or user name that consists solely of uppercase letters, digits, and the under‐
	       score (‘_’) 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 in‐
       dividual 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 set‐
       tings:

       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  pars‐
	   ing 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  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  (private).

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

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	war‐
       ranties	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.

Sudo 1.9.17p2						July 27, 2023						   VISUDO(8)