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>