Provided by: sysvinit-utils_2.88dsf-41ubuntu6.3_amd64 bug

NAME

       sulogin - Single-user login

SYNOPSIS

       sulogin [ -e ] [ -p ] [ -t SECONDS ] [ TTY ]

DESCRIPTION

       sulogin is 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 the boot loader (e.g., grub(8)) passes it the -b
       option.

       The user is prompted

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

       If  the  root account is locked, as is the default on Ubuntu, no password prompt is displayed and sulogin
       behaves as if the correct password were entered.

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

       If the -t option is used then the program only waits the given number of seconds for user input.

       If  the  -p  option  is  used then the single-user shell is invoked with a dash as the first character in
       argv[0].  This causes the shell process 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 option to init. To boot the system into single user mode, with
       the  root  file  system  mounted  read/write, using a special "fail safe" 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 method (getpwnam) first.  Then, if the -e option  was
       specified, sulogin examines these files directly to find the root password:

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

       If  they  are damaged or nonexistent, sulogin will start a root shell without asking for a password. Only
       use the -e option if you are sure the console is physically protected against unauthorized access.

AUTHOR

       Miquel van Smoorenburg <miquels@cistron.nl>

SEE ALSO

       init(8), inittab(5).

                                                   17 Jan 2006                                        SULOGIN(8)