visudo edits the sudoers file in a safe fashion
visudo is a command-line utility that allows editing of the
/etc/sudoers file in a safe fashion. It opens
/etc/sudoers, using the vi editor's interface by default (although this can be changed by setting the shell's
EDITOR environment variable to a different text editor), prevents multiple simultaneous edits with locks, performs sanity checks and checks for parse errors.
Source: [Wikipedia] - visudo (command)