sulogin — Single-user login


sulogin [options] [tty]


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):

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).

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


−e, −−force

If the default method of obtaining the root password via getpwnam(3) from the system fails, manually examine /etc/passwd and /etc/shadow to get the password. 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.

−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.


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.


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


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

  -*- coding: UTF-8 -*-
Copyright (C) 1998-2006 Miquel van Smoorenburg.
Copyright (C) 2012 Karel Zak <>

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