visudo (8)

Leading comments

 Copyright (c) 1996,1998-2005, 2007-2017
	Todd C. Miller <Todd.Miller@courtesan.com>

 Permission to use, copy, modify, and distribute this software for any
 purpose with or without fee is hereby granted, provided that the above
 copyright notice and this permission notice appear in all copies.

 THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR B...

(The comments found at the beginning of the groff file "man8/visudo.8".)

NAME

visudo - edit the sudoers file

SYNOPSIS

visudo [-chqsV ] [-f sudoers ] [-x output_file ]

DESCRIPTION

groff Fl m Ns Cm doc Ar edits the sudoers file in a safe fashion, analogous to vipw(8). groff Fl m Ns Cm doc Ar locks the sudoers file against multiple simultaneous edits, provides basic sanity checks, and checks for parse errors. If the sudoers file is currently being edited you will receive a message to try again later.

There is a hard-coded list of one or more editors that groff Fl m Ns Cm doc Ar will use set at compile-time that may be overridden via the editor sudoers Default variable. This list defaults to /usr/bin/editor Normally, groff Fl m Ns Cm doc Ar does not honor the VISUAL or EDITOR environment variables unless they contain an editor in the aforementioned editors list. However, if groff Fl m Ns Cm doc Ar is configured with the --with-env-editor option or the env_editor Default variable is set in sudoers groff Fl m Ns Cm doc Ar will use any the editor defines by VISUAL or EDITOR Note that this can be a security hole since it allows the user to execute any program they wish simply by setting VISUAL or EDITOR

groff Fl m Ns Cm doc Ar parses the sudoers file after the edit and will not save the changes if there is a syntax error. Upon finding an error, groff Fl m Ns Cm doc Ar 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 care because if groff Fl m Ns Cm doc Ar believes there to be a parse 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 parse error has been detected, the cursor will be placed on the line where the error occurred (if the editor supports this feature).

The options are as follows:

-c , -check

Enable check-only mode. The existing sudoers file will be checked for syntax errors, 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, groff Fl m Ns Cm doc Ar will exit with a value of 0. If an error is encountered, groff Fl m Ns Cm doc Ar will exit with a value of 1.

-f sudoers , --file = sudoers

Specify an alternate sudoers file location. With this option, groff Fl m Ns Cm doc Ar will edit (or check) the sudoers file of your choice, instead of the default, /etc/sudoers The lock file used is the specified sudoers file with ``.tmp'' appended to it. In check-only mode only, the argument to -f may be `-' , indicating that sudoers will be read from the standard input.

-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 used before it is defined, groff Fl m Ns Cm doc Ar will consider this a parse 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 groff Fl m Ns Cm doc Ar and sudoers grammar versions and exit.

-x output_file , --export = output_file

Export a sudoers in JSON format and write it to output_file If output_file is `-' , the exported sudoers policy will be written to the standard output. By default, /etc/sudoers (and any files it includes) will be exported. The -f option can be used to specify a different sudoers file to export. The exported format is intended to be easier for third-party applications to parse than the traditional sudoers format. The various values have explicit types which removes much of the ambiguity of the sudoers format.

Debugging and sudoers plugin arguments

groff Fl m Ns Cm doc Ar versions 1.8.4 and higher support a flexible debugging framework that is configured via Debug lines in the sudo.conf5 file.

Starting with sudo 1.8.12, groff Fl m Ns Cm doc Ar 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.conf5, please refer to its manual.

ENVIRONMENT

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

VISUAL

Invoked by groff Fl m Ns Cm doc Ar as the editor to use

EDITOR

Used by groff Fl m Ns Cm doc Ar if VISUAL is not set

FILES

/etc/sudo.conf

Sudo front end configuration

/etc/sudoers

List of who can run what

/etc/sudoers.tmp

Lock file for visudo

DIAGNOSTICS

sudoers file busy, try again later.

Someone else is currently editing the sudoers file.

/etc/sudoers.tmp: Permission denied

You didn't run groff Fl m Ns Cm doc Ar as root.

Can't find you in the passwd database

Your user ID does not appear in the system passwd file.

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 Po sudo will not complain Pc . 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. 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. This is only a warning by default as sudo will ignore cycles when parsing the sudoers file.

visudo: /etc/sudoers: input and output files must be different

The -x flag was used and the specified output_file has the same path name as the sudoers file to export.

SEE ALSO

vi(1), sudo.conf5, sudoers(5), sudo(8), vipw(8)

AUTHORS

Many people have worked on sudo over the years; this version consists of code written primarily by:

An Todd C. Miller

See the CONTRIBUTORS file in the sudo distribution (www.sudo.ws/contributors.html 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 groff Fl m Ns Cm doc Ar allows shell escapes.

BUGS

If you feel you have found a bug in , please submit a bug report at bugzilla.sudo.ws

SUPPORT

Limited free support is available via the sudo-users mailing list, see www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search the archives.

DISCLAIMER

groff Fl m Ns Cm doc Ar 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 www.sudo.ws/license.html for complete details.