NAME

xlock − Locks the local X display till a password is entered. 
 

SYNOPSIS

xlock [ −display dsp ] [ −mode mode ] [ −time timeout ] [ −count n ] [ −nice nicelevel ] [ −font fontname ] [ −color ] [ −lock ] [ −root ] [ −xhost ] [ −screensaver ] [ −echokeys ] [ −v ] [ −install ]
 

DESCRIPTION

xlock locks the X server till the user enters their password at the keyboard.  While xlock is running, all new server connections are refused.  The screen saver is disabled.  The mouse cursor is turned off.  The screen is blanked and a changing pattern is put on the screen.  The pattern changes after timeout seconds.  If a key or a mouse button is pressed then the user is prompted for the password of the user who started xlock. 
 
If the correct password is typed, then the screen is unlocked and the X server is restored.  When typing the password Control-U and Control-H are active as kill and erase respectively.  To return to the locked screen, click in the small icon version of the changing pattern.
 

OPTIONS

−display  dsp
The display option sets the X11 display to lock.  xlock follows standard X11 naming convention for displays as in machinename:server.screen, if you are only displaying the lockscreen animation, (see -lock ), but will not allow one to lock another server’s display thus only unix:server.screen, localhost:server.screen, and :server.screen are allowed for dsp.  Where server is which X11 server socket to connect to and screen is which head to display the pattern on. 

−mode  modename
As of this writing there are three display modes supported.

hop Hop mode shows the "real plane fractals" from the September 1986 issue of Scientific American. 

life Life mode shows Conway’s game of life. 

qix Qix mode shows the spinning lines similar to the old video game by the same name. 

−time  timeout
The time option sets the number of seconds that each unique fractal will remain on the screen before being replaced by the next one to timeout. 

−count  n
The count option sets the speed at which a mode will operate.  The different modes interpret this value differently.  For ’hop’ and ’qix’ this sets the number of pixels and lines respectively to draw in each color.  These patterns are calculated in batches of n objects, then sent to the server in a single color.  Faster machines, expecially machines with floating point hardware can set this to a higher number and still have fast changing patterns.  The ’life’ mode, in contrast interprets this number as the number of milliseconds to delay after each generation of the "critters".  A low number here makes the pattern change rapidly, where 1000 means wait a second between generations. 

−font  fontname
The font option sets the font to be used on the prompt screen. 

−nice  nicelevel
The nice option sets system nicelevel of the xlock process to nicelevel . 

−color
The color option causes xlock to display monochrome, (black and white) pixels rather than the default colored ones on color displays. 

−lock
The lock option causes xlock to only draw the patterns and not lock the display.  A keypress or a mouse click will terminate the screen saver. 

−root
The root option allows the root password to unlock the server as well as the user who started xlock. 

−xhost
This option is simply a hack for the paranoid, who don’t want to disable the access control list, but still want the local server to prompt for a password. This way if xlock is killed -KILL, the access control list is not lost.

−screensaver
By default xlock will disable the normal X server’s screen saver since it is in effect a replacement for it.  Since it is possible to set delay parameters long enough to cause phosphor burn on some displays, this option will turn back on the default screensaver which is very careful to keep most of the screen black.

−echokeys
The echokeys option causes xlock to echo ’?’ characters for each key typed into the password prompt.  Some consider this a security risk, so the default is to not echo anything. 

−v Verbose mode, tells what options it is going to use. 

−install
Forcibly install the colormap. This violates ICCCM standards and will not work with ICCCM compliant window managers. This option exists for backward compatibility with older versions of xlock.
 

BUGS

"kill -KILL xlock " causes server to be unusable, since xlock has removed all hosts (including localhost) from the access control list to lock out all new X clients, and SIGKILL cannot be caught by any program, xlock will terminate before restoring the access control list.  This will leave the X server in a state where "you can no longer connect to that server, and this operation cannot be reversed short of resetting the server."  -From the X11R2 Xlib Documentation page 140. 

SEE ALSO

X(1), Xlib Documentation. 
 

AUTHOR

 Patrick J. Naughton (naughton@sun.com)
 Window Systems Group
 Sun Microsystems, Inc.
 Mountain View, CA  94043
 415/336-1080
 

COPYRIGHT

Copyright (c) 1988-90 by Patrick J. Naughton and Sun Microsystems, Inc. 
 
Permission to use, copy, modify, and distribute this software and its documentation for any purpose and without fee is hereby granted, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation.
 

CONTRIBUTORS

  milliken@heron.bbn.comkarlton@wsl.dec.com
  dana@thumper.bellcore.comvesper@3d.dec.comflar@sun.com

Amiga Unix  —  Last change: 18 Feb 1990