SULOGIN (8)
- 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 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 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,
/etc/shadow (if present)
AUTHOR
Miquel van Smoorenburg <miquels@cistron.nl>
SEE ALSO
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