redhat man page for sulogin

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

NAME
       sulogin -- Single-user login

SYNOPSIS
       sulogin [ -e ] [ -p ] [ -t timeout ] [ tty-device ]

DESCRIPTION
       sulogin can be invoked by init(8) when the system goes into single user mode (this is done through an entry in inittab(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/con-
       sole).

       If the -p flag was set, the single-user shell will be invoked with a dash as the first character in argv[0]. That will cause most shells to
       behave as a login shell. The default is not to do this, so that the shell will not read /etc/profile or $HOME/.profile at startup.

       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.

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

       This  is  very  valuable  together  with  the  -b flag to init. To boot the system into single 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

FALLBACK METHODS
       sulogin checks the root password using the standard methods first.  If the -e option was specified, 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/passwd,
       /etc/shadow (if present)

AUTHOR
       Miquel van Smoorenburg <miquels@cistron.nl>

SEE ALSO
       init(8), inittab(5).

								    11 Sep 2000 							SULOGIN(8)