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sulogin(8) [linux man page]

SULOGIN(8)						Linux System Administrator's Manual						SULOGIN(8)

NAME
sulogin - Single-user login SYNOPSIS
sulogin [ -e ] [ -p ] [ -t SECONDS ] [ TTY ] DESCRIPTION
sulogin is 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 the boot loader (e.g., grub(8)) passes it the -b option. The user is prompted Give root password for system maintenance (or type Control-D for normal startup): If the root account is locked, as is the default on Ubuntu, no password prompt is displayed and sulogin behaves as if the correct password were entered. sulogin will be connected to the current terminal, or to the optional device that can be specified on the command line (typically /dev/con- sole). If the -t option is used then the program only waits the given number of seconds for user input. If the -p option is used then the single-user shell is invoked with a dash as the first character in argv[0]. This causes the shell process 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 option to init. To boot the system into single user mode, with the root file system mounted read/write, using a special "fail safe" shell that is statically linked (this example is valid for the LILO bootprompt) boot: linux -b rw sushell=/sbin/sash FALLBACK METHODS
sulogin checks the root password using the standard method (getpwnam) first. Then, if the -e option was specified, sulogin examines these files directly to find the root password: /etc/passwd, /etc/shadow (if present) 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. AUTHOR
Miquel van Smoorenburg <miquels@cistron.nl> SEE ALSO
init(8), inittab(5). 17 Jan 2006 SULOGIN(8)

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sulogin(1M)                                               System Administration Commands                                               sulogin(1M)

NAME
sulogin - access single-user mode SYNOPSIS
sulogin DESCRIPTION
The sulogin utility is automatically invoked by init when the system is first started. It prompts the user to type the root password to enter system maintenance mode (single-user mode) or to type EOF (typically <CTRL-D>) for normal startup (multi-user mode). The user should never directly invoke sulogin. The sulogin utility can prompt the user to enter the root password on a variable number of serial console devices, in addition to the tra- ditional console device. See consadm(1M) and msglog(7D) for a description of how to configure a serial device to display the single-user login prompt. FILES
/etc/default/sulogin Default value can be set for the following flag: PASSREQ Determines if login requires a password. Default is PASSREQ=YES. /etc/default/login Default value can be set for the following flag: SLEEPTIME If present, sets the number of seconds to wait before login failure is printed to the screen and another login attempt is allowed. Default is 4 seconds. Minimum is 0 seconds. Maximum is 5 seconds. Both su(1M) and login(1) are affected by the value of SLEEPTIME. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsr | +-----------------------------+-----------------------------+ SEE ALSO
login(1), consadm(1M), init(1M), su(1M), attributes(5), msglog(7D) SunOS 5.10 25 Sep 2002 sulogin(1M)
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