# x11lock: my own minimalistic lock screen for x11

i need one functionality from a lock screen: prevent people "accidentally" interact with my machine such as nosy kids or coworkers. but i generally trust people around me so this is more about putting up a fence rather than having an impenetrable protection. and when i come back to my machine, i want to quickly and conveniently unlock the screen (ideally one handed) so that i can continue where i left off. but most lock screen software want you to enter your login password to unlock it and don't allow for customization. for me that's overkill, let me just configure some secret magic key combo to unlock it and i'm happy.

since most lock screen software doesn't let you do that and are super bloated, i wrote my own. writing a screensaver is surprisingly simple. you need to do 3 things:

• run in the background to notice the inactivity timeout events,
• blank the screen and grab the input on timeout,
• allow unlocking the screen.

you don't even need to implement stuff like timeout configuration, just use `xset s` to configure those and have the software follow those settings. in fact, x11 will announce when the screensaver needs to activate, the daemon just needs to listen for those events. even daemonizing is pretty much a single line in c with its `daemon()` function from the libc. all this leads to a very straighforward 220 lines of c code: https://github.com/ypsu/cfg/blob/master/utils/x11lock.c.

this is how i configure and start my screensaver daemon:

  xset s noblank
  xset s 900
  xset dpms 1200 1200 1200
  x11lock start

it also supports manual activation. "x11lock activate" just sends the daemon a sigusr1 which starts the lock window immediately. i have this binding in my .i3/config:

  bindsym $mod+Mod1+l exec x11lock activate
  bindsym $mod+Scroll_Lock exec x11lock activate

i admit there's lot of stuff missing from it like the ability to customize the key combo (rather than being hardcoded) and proper multimonitor support. but i don't need those so this is completely fine for me for now. it probably wouldn't be too hard to add those if i really wanted to.

btw, even xscreensaver's author thinks most screensaver software is bloated:

• https://www.jwz.org/xscreensaver/toolkits.html
• https://www.jwz.org/blog/2021/01/i-told-you-so-2021-edition

anyway, i'm using this minimalistic screensaver at home for a while now and works perfectly. i'm using a key combo that is hard to enter randomly by mashing keys. it's sometimes even hard for me to enter intentionally. but it was fine after i got the hang of it.

published on 2023-01-02

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