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
           Print version 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.

REPORTING BUGS         top

       For bug reports, use the issue tracker at

AVAILABILITY         top

       The sulogin command is part of the util-linux package which can
       be downloaded from Linux Kernel Archive
       <>. 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
       2023-12-22. (At that time, the date of the most recent commit
       that was found in the repository was 2023-12-14.) 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 2.39.594-1e0ad      2023-07-19                     SULOGIN(8)

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