sulogin -- Single-user login
SYNOPSIS
sulogin [ -t timeout ] [ -p ] [ tty-device ]
DESCRIPTION
sulogin can be invoked by init(8) when the system goes
into single user mode (this is done through an entry in
inittab(5)). Init also tries to execute sulogin when it is
passed the -b flag from the bootmonitor (eg, LILO).
The user is prompted
Give root password for system maintenance
(or type Control-D for normal startup):
sulogin will connected to the current terminal, or to the
optional device that can be specified on the command line
(typically /dev/console).
If the -p flag was set, the single-user shell will be
invoked with a dash as the first character in argv[0].
That will cause most shells to behave as a login shell.
The default is not to do this, so that the shell will not
read /etc/profile or $HOME/.profile at startup.
After the user exits the single-user shell, or presses
control-d at the prompt, the system will (continue to)
boot to the default runlevel.
ENVIRONMENT VARIABLES
sulogin looks for the environment variable SUSHELL or
sushell to determine what shell to start. If the environ
ment 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 is very valuable together with the -b flag to init.
To boot the system into single user mode, with the root
file system mounted read/write, using a special "failsafe"
shell that is statically linked (this example is valid for
the LILO bootprompt)
boot: linux -b rw sushell=/sbin/sash
FILES
sulogin examines the next files to find the root password.
If they are damaged, or non-existant, it will use fallback
methods that even go so far as to provide you with a shell
prompt without asking for the root password if they are
irrepairably damaged.
/etc/passwd,
AUTHOR
Miquel van Smoorenburg <miquels@cistron.nl>
SEE ALSO
init(8), inittab(5).
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