SULOGIN(8)     Linux System Administrator's Manual     SULOGIN(8)

       sulogin -- Single-user login

       sulogin [ -t timeout ] [ tty-device ]

       sulogin  is  invoked  by init(8) when the system goes into
       single user mode (this is done through an entry  in  init-
       tab(5)).  Init  also  tries  to execute sulogin when it is
       passed the -b flag from the bootmonitor (eg, LILO).

       The user is prompted

            Give root password for system maintenance
            (or type Control-D for normal startup):

       sulogin will connected to the current terminal, or to  the
       optional  device that can be specified on the command line
       (typically /dev/console).

       After the user exits the  single-user  shell,  or  presses
       control-d  at  the  prompt,  the system will (continue to)
       boot to the default runlevel.

       sulogin looks for  the  environment  variable  SUSHELL  or
       sushell  to determine what shell to start. If the environ-
       ment variable is not set, it will try  to  execute  root's
       shell from /etc/passwd. If that fails it will fall back to

       This is very valuable together with the -b flag  to  init.
       To  boot  the  system  into singe user mode, with the root
       file system mounted read/write, using a special "failsafe"
       shell that is statically linked (this example is valid for
       the LILO bootprompt)

       boot: linux -b rw sushell=/sbin/sash

       sulogin examines the next files to find the root password.
       If they are damaged, or non-existant, it will use fallback
       methods that even go so far as to provide you with a shell
       prompt  without  asking  for the root password if they are
       irrepairably damaged.

       /etc/shadow (if present)

       Miquel van Smoorenburg <>

       init(8), inittab(5).

                           15 May 1996                          1