Interesting systemd features you may not know about

I've always thought of systemd as a fairly boring piece of plumbing, that boots your system and runs background services. I also knew there was enormous controversy when it first came out, but I hadn't really dived much into it past this. Systemd actually has tonnes of interesting features, that I think are even more useful for running throwaway agent-written code. Note this is all Linux only - sorry Mac users, there's no real equivalent of systemd on macOS (launchd covers some of the cron-style stuff, but not the resource limits). Easy memory/CPU caps per process You may have experienced this before. You have an agent write a script, perhaps to do some data analysis. It has a terrible memory leak, and suddenly your machine freezes and (hopefully) the kernel resumes after a bit with an OOM error. I've had this a few times, and it's very annoying. Turns out systemd has an easy way to limit processes and any subprocesses, with MemoryMax and CPUQuota. These actually use the same…