xscreensaver: How do I run a script on unlock?

Question

I'd like to run a screen if the XFCE session is locked and unlocked. Is there a way that I can intercept this and perform certain actions when the desktop is locked or unlocked?

I see that it is possible in Ubuntu; but I'd like to achieve this in Xubuntu.

I can't seem to find any events triggered by xscreensaver when it quits...

Solution

xscreensaver has a -watch option:

-watch    Prints a line each time the screensaver changes state: when the screen blanks, locks, unblanks, or when the running hack is changed. This option never returns; it is intended for use by shell scripts that want to react to the screensaver in some way.¹

The UNBLANK state is what you are looking for. The manual includes an example script using these options.

^{1. http://www.jwz.org/xscreensaver/man3.html}

Comments

[KB22]

Is there a way to tell xfce4 to run xscreensaver in the described way and have a script listen to its output?