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
       virtual 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 variable 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>