sulogin(8) — Linux manual page


SULOGIN(8)                System Administration               SULOGIN(8)

NAME         top

       sulogin - single-user login

SYNOPSIS         top

       sulogin [options] [tty]

DESCRIPTION         top

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

       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         top

       -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 without 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         top

       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.

AUTHORS         top

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

AVAILABILITY         top

       The sulogin command is part of the util-linux package and is
       available from Linux Kernel Archive 

COLOPHON         top

       This page is part of the util-linux (a random collection of Linux
       utilities) project.  Information about the project can be found
       at ⟨⟩.  If you
       have a bug report for this manual page, send it to  This page was obtained from the
       project's upstream Git repository
       ⟨git://⟩ on
       2021-03-21.  (At that time, the date of the most recent commit
       that was found in the repository was 2021-03-19.)  If you
       discover any rendering problems in this HTML version of the page,
       or you believe there is a better or more up-to-date source for
       the page, or you have corrections or improvements to the
       information in this COLOPHON (which is not part of the original
       manual page), send a mail to

util-linux                      July 2014                     SULOGIN(8)

Pages that refer to this page: passwd(5@@shadow-utils)shadow(5)