NAME
xlock - Locks the local X display until a password is
entered.

SYNOPSIS
xlock [ -display dsp ] [ -help ] [ -nameresource-name ] [
-resources ] [ -/+remote ] [ -/+mono ] [ -/+nolock ] [ -
/+allowroot ] [ -/+enablesaver ] [ -/+allowaccess ] [ -
/+echokeys ] [ -/+usefirst ] [ -/+v ] [ -delay usecs ] [
-batchcount num ] [ -nice level ] [ -timeout seconds ] [
-saturation value ] [ -font fontname ] [ -bg color ] [ -fg
color ] [ -mode mode ] [ -username textstring ] [ -password
textstring ] [ -info textstring ] [ -validate textstring ] [
-invalid textstring ]

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. 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
locks all available screens on a given server, and res-
tricts you to locking only a local server such as
unix:0, localhost:0, or :0 unless you set the -remote
option.

-name resource-name
resource-name is used instead of XLock when looking for
resources to configure xlock.

-mode modename
As of this writing there are eight display modes sup-
ported (plus one more for random selection of one of
the eight).

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.

image Image mode shows several sun logos randomly
appearing on the screen.

swarm Swarm mode shows a swarm of bees following a wasp.

rotor Rotor mode shows a swirling rotorlike thing.

pyro Pyro mode shows fireworks.

flame Flame mode shows wierd but cool cosmic flame frac-
tals.

worm Worm mode shows wiggly worms...

blank Blank mode shows nothing but a black screen.

random Random mode picks a random mode from all of the
above except blank mode.

-delay usecs
The delay option sets the speed at which a mode will
operate. It simply sets the number of microseconds to
delay between batches of "hopalong pixels", "qix
lines", "life generations", "image blits", and "swarm
motions". In blank mode, it is important to set this
to some small number of seconds, because the keyboard
and mouse are only checked after each delay, so you
cannot set the delay too high, but a delay of zero
would needlessly consume cpu checking for mouse and
keyboard input in a tight loop, since blank mode has no
work to do.

-batchcount num
The batchcount option sets number of things to do per
batch to num . In hop mode this refers to the number of
pixels rendered in the same color. In life mode it is
the number of generations to let each species live. In
qix mode it is the number of lines rendered in the same
color. In image mode it is the number of sunlogos on
screen at once. In swarm mode it is the number of
bees. In rotor mode it is the number of rotor thingys
which whirr... In pyro mode it is the maximum number
flying rockets at one time. In flame mode it is the
number of levels to recurse (larger = more complex).
In worm mode it is the number of worms. In blank mode
it means nothing.

-nice nicelevel
The nice option sets system nicelevel of the xlock pro-
cess to nicelevel .

-timeout seconds
The timeout option sets the number of seconds before
the password screen will time out.

-saturation value
The saturation option sets saturation of the color ramp
used to value . 0 is grayscale and 1 is very rich
color. 0.4 is a nice pastel.

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

-fg color
The fg option sets the color of the text on the
password screen to color .

-bg color
The bg option sets the color of the background on the
password screen to color .

-username textstring
textstring is shown in front of user name, defaults to
"Name: ".

-password textstring
textstring is the password prompt string, defaults to
"Password: ".

-info textstring
textstring is an informational message to tell the user
what to do, defaults to "Enter password to unlock;
select icon to lock.".

-validate textstring
textstring -validate message shown while validating the
password, defaults to "Validating login..."

-invalid textstring
textstring -invalid message shown when password is
invalid, defaults to "Invalid login."

-resources
The resources option prints the default resource file
for xlock to standard output.

-/+remote
The remote option tells xlock to not stop you from
locking remote X11 servers. This option should be used
with care and is intended mainly to lock X11 terminals
which cannot run xlock locally. If you lock someone
else’s workstation, they will have to know your pass-
word to unlock it.

-/+mono
The mono option causes xlock to display monochrome,
(black and white) pixels rather than the default
colored ones on color displays

+/-nolock
The nolock option causes xlock to only draw the pat-
terns and not lock the display. A keypress or a mouse
click will terminate the screen saver.

-/+allowroot
The allowroot option allows the root password to unlock
the server as well as the user who started xlock.

-/+enablesaver
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.

-/+allowaccess
This option is required for servers which do not allow
clients to modify the host access control list. It is
also useful if you need to run x clients on a server
which is locked for some reason... When allowaccess is
true, the X11 server is left open for clients to attach
and thus lowers the inherent security of this lock-
screen. A side effect of using this option is that if
xlock is killed -KILL, the access control list is not
lost.

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

-/+usefirst
The usefirst option causes xlock to use the keystroke
which got you to the password screen as the first char-
acter in the password. The default is to ignore the
first key pressed.

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

BUGS
"kill -KILL xlock " causes the server that was locked to be
unusable, since all hosts (including localhost) were removed
from the access control list to lock out new X clients, and
since xlock couldn’t catch SIGKILL, it terminated 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 unless you
reset the server." -From the X11R4 Xlib
Documentation, Chapter 7.

NCD terminals do not allow xlock to remove all the hosts
from the access control list. Therefore you will need to
use the "-remote" and "-noaccess" switches. If you happen
to run without "-noaccess" on an NCD terminal, xlock won’t
work and you will need to reboot the terminal, or simply go
into the SETUP menus, under ’Network Parameters’, and turn
off TCP/IP access control.