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 invokers 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.