VLOCK(1)							Linux User's Manual							  VLOCK(1)

NAME

       vlock - Virtual Console lock program

SYNOPSIS

       vlock [ -hv ]

       vlock [ -acns ] [ -t <timeout> ] [ plugins... ]

DESCRIPTION

       vlock  is  a  program  to lock one or more sessions on the Linux console.  This is especially useful for Linux machines which have multiple
       users with access to the console.  One user may lock his or her session(s) while still allowing other users to use the system on other vir-
       tual consoles.  If desired, the entire console may be locked and virtual console switching disabled.

       By  default,  only  the	current  VC  (virtual  console) is locked.  With the -a,--all option all VCs are locked.  The locked VCs cannot be
       unlocked without the invoker's password or the root password.  The root password will always be able to unlock any or all sessions,  unless
       disabled at compile time.

       Please  note  that  it  is entirely possible to completely lock yourself out of the console with the -a,--all option if you cannot remember
       your password!  Unless you are able to kill vlock by logging in remotely via a serial terminal or network, a hard reset is the only  method
       of ``unlocking'' the display.

       When  locking  the  entire console display it is sometimes still possible to kill vlock using the Secure Access Key (SAK) or other commands
       that are available through the SysRq mechanism.	When the -s,--disable-sysrq and -a,--all options are given the SysRq mechanism is disabled
       while vlock is running.	See /usr/src/linux/Documentation/sysrq.txt for more details.

       vlock  works for console sessions primarily.  To lock the entire console display from an X session use the -n,--new option.  This will make
       vlock switch to an empty virtual console to lock the display.

       The options -n,--new, -s,--disable-sysrq, and -t,--timeout only work if vlock is compiled with plugin support.  See the PLUGINS section for
       more information.

OPTIONS

       -a,--all

	      Lock all console sessions and disable VC switching.

       -c,--current

	      Lock the current session (this is the default).

       -n,--new

	      Switch to a new virtual console before locking all console sessions.

       -s,--disable-sysrq

	      Disable the SysRq mechanism while consoles are locked.  This option only works if the -a,--all option given.

       -t,--timeout <seconds>

	      Specify the timeout for the screensaver plugins.	See vlock-plugins(5) for more information.

       -h,--help

	      Print a brief help message.

       -v,--version

	      Print the version number.

ENVIRONMENT VARIABLES

       The following environment variables can be used to change vlock's behavior:

       USER

	      If  this	variable is when vlock is run as root (uid 0) vlock locks the screen as this user instead of root.  The root password will
	      still be able to unlock the session, unless disabled at compile time.

       VLOCK_ALL_MESSAGE

	      If this variable is set and all consoles are locked its contents will be used as the locking message instead of the default message.

       VLOCK_CURRENT_MESSAGE

	      If this variable is set and only the current consoles is locked its contents will be used as the	locking  message  instead  of  the
	      default message.

       VLOCK_MESSAGE

	      If  this	variable  is  set  its contents will be used as the locking message instead of the default.  This overrides the former two
	      variables.

       VLOCK_PLUGINS

	      If this variable is set it is interpreted as a space separated list of plugins that will be loaded when vlock starts additionally to
	      the ones listed on the command line.

       VLOCK_TIMEOUT

	      Set  this variable to specify the timeout (in seconds) after which the screen saver plugins (if any) will be invoked.  If this vari-
	      able is unset or set to an invalid value or 0 no timeout is used.  See vlock-plugins(5) for more information about plugins.

       VLOCK_PROMPT_TIMEOUT

	      Set this variable to specify the amount of time (in seconds) you will have to enter your password at the password prompt.   If  this
	      variable	is  unset  or  set to an invalid value or 0 no timeout is used.  Warning: If this value is too low, you may not be able to
	      unlock your session.

FILES

       ~/.vlockrc

	      This file is read by vlock on startup if it exists.  All the variables mentioned above can be set here.

SECURITY

       See the SECURITY file in the vlock distribution for more information.

SEE ALSO

       vlock-main(8), vlock-plugins(5)

AUTHORS

       Michael K. Johnson <http://danlj.org/mkj/>

       Frank Benkstein <frank-vlock@benkstein.net>

Linux								   28 July 2007 							  VLOCK(1)