Member Avatar for alaa sam

hey everyone
well my screen lock doesn't work also ctrl+alt_l doesn't lock it , also after a suspend it doesn't lock even though it's set to do so
what can I do to make it work ??
I use ubuntu 12.04

Edited by alaa sam
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Brief summary and next steps (building on 's report and 's hint about shortcuts): the lock/key shortcut can be a red herring — the usual causes on Precise are (a) the locker daemon not running or being replaced by another locker, (b) a conflict between different locker packages, or (c) suspend/resume hooks failing to trigger the locker. The checklist below shows focused diagnostics and low-risk fixes to try in order.

First, identify the locker and test manual locking. Run these commands and note the output:

dpkg -l | egrep 'gnome-screensaver|xscreensaver|light-locker|cinnamon-screensaver'
ps aux | egrep 'gnome-screensaver|xscreensaver|light-locker' | grep -v egrep

# test locking (one of these will work if a compatible locker/daemon is running)
gnome-screensaver-command -l
xdg-screensaver lock
dm-tool lock

If gnome-screensaver-command -l does nothing, the daemon may not be running; the daemon must be present and autostart enabled for automatic locking to work. You can also run the screensaver in debug mode to capture errors (gnome-screensaver --no-daemon --debug) and check its logs. (manpages.org)

If you installed a different screensaver/locker (for example XScreenSaver) from a post‑install guide, that can conflict with Unity/GNOME’s locker. XScreenSaver advises removing other screensaver packages when used on GNOME — either pick XScreenSaver or the GNOME screensaver, don’t run both. If you prefer the Unity default, remove the alternative and reinstall/re-enable gnome-screensaver. ()

For suspend/resume problems, check resume logs and pm hooks:

sudo tail -n 200 /var/log/pm-suspend.log
grep -i screensaver ~/.xsession-errors /var/log/syslog /var/log/pm-suspend.log

If the locker is started but you still resume to a blank/white/unresponsive screen, the pm-utils hooks or a failing resume script may be to blame; the pm log is the right place to look. (askubuntu.com)

Quick checklist: confirm which locker is installed and running, test manual lock, run gnome-screensaver in debug to capture errors, remove conflicting lockers if you want the Unity default, and inspect /var/log/pm-suspend.log after a failed resume. If none of this isolates the problem, collect the gnome-screensaver debug output and relevant logs and file a bug (the Ubuntu debugging page shows exact data to attach). If you use LightDM/light-locker instead, dm-tool lock / light-locker options are the equivalent commands to test. (wiki.ubuntu.com)

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Member Avatar for JasonHippy

OK, it's been a while since I took a look at Unity, so my memory of it is a little hazy. But at a guess, you might want to check that the keyboard shortcut to lock the screen hasn't been changed or disabled somehow.

If you go to System settings->Keyboard->Shortcuts, then take a look for an entry for locking the screen. You might find that the shortcut has been disabled, or changed, or possibly removed.

If you get there and it says that ctrl+alt+L is still the combination and it's enabled, but it's still not working; try changing they keyboard shortcut to something else (like ctrl+shift+alt+L) to see if that works.

If that fails, then you've probably found a bug in Unity. In which case, you might want to report the problem to the Ubuntu devs.

Member Avatar for alaa sam

The shortcut isn't disabled , this happened after I followed some steps written in an article titled "10 things to do after installing ubuntu 12.04 lts " .
sometimes it doesn't lock only the screen becomes white and nothing responds .
what shoul I do .

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