linux - vipw (8)

     vipw - edit the password file

     vipw

     Vipw edits the password file after setting the appropriate locks, and
     does any necessary processing after the password file is unlocked.  If
     the password file is already locked for editing by another user, vipw
     will ask you to try again later. The default editor for vipw is vi(1).

     If the following environment variable exists it will be utilized by vipw:

     EDITOR  The editor specified by the string EDITOR will be invoked instead
             of the default editor vi(1).

     passwd(1),  vi(1),  passwd(5)

     The vipw command appeared in 4.0BSD.