slock man page
slock — simple X screen locker
|slock||[-v] [cmd [arg ...]]|
slock is a simple X screen locker. If provided, cmd [arg ...] is executed after the screen has been locked.
Print version information to stdout and exit.
To make sure a locked screen can not be bypassed by switching VTs or killing the X server with Ctrl+Alt+Backspace, it is recommended to disable both in xorg.conf(5) for maximum security:
Section "ServerFlags" Option "DontVTSwitch" "True" Option "DontZap" "True" EndSection
$ slock /usr/sbin/s2ram
slock can be customized by creating a custom config.h from config.def.h and (re)compiling the source code. This keeps it fast, secure and simple.