How can a program detect if it is running as a systemd daemon?

问题

Is there any way to detect in a program that it is run by systemd as a daemon?

systemd API

sd_booted()

is used to detected if the whole system is booted by systemd, but says nothing about the program itself.

Thanks

回答1:

Get the parent process id and see whether that process is systemd.

回答2:

You could set a magic environment variable in the daemon's service file and look for this variable.

来源：https://stackoverflow.com/questions/39368185/how-can-a-program-detect-if-it-is-running-as-a-systemd-daemon