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
sulogin will be connected to the current terminal, or to the optional
tty device that can be specified on the command line (typically
When the user exits from the single-user shell, or presses control-D
at the prompt, the system will continue to boot.
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 rootshell without asking for a password.
Only use the -e option if you are sure the console is
physically protected against unauthorized access.
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.
Display help text and exit.
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.
This page is part of the util-linux (a random collection of Linux
utilities) project. Information about the project can be found at
⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩. If you have a
bug report for this manual page, send it to
email@example.com. This page was obtained from the
project's upstream Git repository
2017-03-13. If you discover any rendering problems in this HTML ver‐
sion 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 man‐
ual page), send a mail to firstname.lastname@example.org
util-linux July 2014 SULOGIN(8)