(C-a x, C-a C-x)
Call a screenlock program (`/local/bin/lck' or `/usr/bin/lock'
or a builtin, if no other is available). Screen does not accept any
command keys until this program terminates. Meanwhile processes in the
windows may continue, as the windows are in the detached state.
The screenlock program may be changed through the environment variable
$LOCKPRG (which must be set in the shell from which screen
is started) and is executed with the user's uid and gid.
Warning: When you leave other shells unlocked and have no password set
on screen, the lock is void: One could easily re-attach from an
unlocked shell. This feature should rather be called
lockterminal.
