vipw, vigr - edit the password, group, shadow-password, or shadow-group file.
vipw and vigr will edit the files
/etc/passwd and /etc/group, respectively. With
the -s flag, they will edit the shadow versions of
those files, /etc/shadow and /etc/gshadow,
respectively. The programs will set the appropriate locks to
prevent file corruption.
When looking for an editor, the programs will first try the
environment variable VISUAL, then the environment
variable EDITOR, and finally the default editor,