locks the sudoers file against multiple simultaneous edits, performs basic validity checks, and checks for syntax errors before installing the edited file
Synopsis:
visudo [-chOPqsV] [[-f] sudoers]
List of options:
-c, --check
Enable check-only mode.
The existing sudoers file (and any other files it includes) will be checked for syntax errors
-f sudoers, --file=sudoers
Specify an alternate sudoers file location, see below.
-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.
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.