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