visudo edits the sudoers file in a safe fashion, analogous to vipw(8). visudo 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 visudo will use set at compile-time that may be overridden via the editor sudoers Default variable. This list defaults to /usr/bin/editor Normally, visudo does not honor the VISUAL or EDITOR environment variables unless they contain an editor in the aforementioned editors list. However, if visudo is configured with the --with-env-editor option or the env_editor Default variable is set in sudoers visudo 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
visudo parses the sudoers file after the edit 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 care because if visudo 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, 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. With this option, visudo 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, visudo 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 visudo 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 visudo
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, 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:
- 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.conf5, please refer to its manual.
vi(1), sudo.conf5, sudoers(5), sudo(8), vipw(8)
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 (https://www.sudo.ws/contributors.html) for an exhaustive list of people who have contributed to sudo
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.