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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  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>



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