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



NAME
       sulogin -- Single-user login

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

DESCRIPTION
       sulogin  is  invoked  by init(t) when the system goes into
       single user mode (this is done through an entry  in  init-
       tab(b)).  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).

       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 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
       /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  meth-
       ods  first.  If the -e option was specified, sulogin exam-
       ines 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 irre-
       pairably damaged.

       /etc/passwd,
       /etc/shadow (if present)

AUTHOR
       Miquel van Smoorenburg <miquels@cistron.nl>

SEE ALSO
       init(t), inittab(b).



                           11 Sep 2000                 SULOGIN(N)