Решение

В КДЕ в разделе «Energy Saving» была нужная фича. Решено для меня

для xscreenserver

programs (class Programs) The graphics hacks which xscreensaver runs when the user is idle. The value of this resource is a multi-line string, one sh-syntax command per line. Each line must con- tain exactly one command: no semicolons, no ampersands.

When the screensaver starts up, one of these is selected (according to the mode set- ting), and run. After the cycle period expires, it is killed, and another is selected and run.

xautolock(1)                General Commands Manual               xautolock(1)

NAME
       xautolock - fire up programs in case of user inactivity under X