sulogin

SULOGIN(8)                   System Administration                  SULOGIN(8)

NAME
       sulogin - single-user login

SYNOPSIS
       sulogin [options] [tty]

DESCRIPTION
       sulogin is invoked by init when the system goes into single-user mode.

       The user is prompted:

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

       If  the root account is locked and --force is specified, no password is
       required.

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

       When the user exits from the single-user shell, or presses control-D at
       the prompt, the system will continue to boot.

OPTIONS
       -e, --force
              If  the  default  method of obtaining the root password from the
              system via  getpwnam(3)  fails,  then  examine  /etc/passwd  and
              /etc/shadow  to get the password.  If these files are damaged or
              nonexistent, or when root account is locked by '!' or '*' at the
              begin of the password then sulogin will start a root shell with-
              out asking for a password.

              Only use the -e option if you are sure the console is physically
              protected against unauthorized access.

       -p, --login-shell
              Specifying this option causes sulogin to start the shell process
              as a login shell.

       -t, --timeout seconds
              Specify the maximum amount of time to wait for user  input.   By
              default, sulogin will wait forever.

       -h, --help
              Display help text and exit.

       -V, --version
              Display version information and exit.

ENVIRONMENT VARIABLES
       sulogin looks for the environment variable SUSHELL or sushell to deter-
       mine 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.

AUTHOR
       sulogin was written by Miquel van Smoorenburg for  sysvinit  and  later
       ported to util-linux by Dave Reisner and Karel Zak.

AVAILABILITY
       The  sulogin command is part of the util-linux package and is available
       from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils/util-
       linux/>.

util-linux                         July 2014                        SULOGIN(8)