Why is the first PID init?

Question

linux

Hey!
Ubuntu has systemd since version 14, but the first PID = init. Why?

USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root         1  0.0  0.0 185136  5716 ?        Ss   08:47   0:01 /sbin/init text

Answer 1

Because init is a symlink in most distributions.

➜ ~ ls /sbin/init -lh
lrwxrwxrwx 1 root root 22 Oct 7 20:38 /sbin/init -> ../lib/systemd/systemd
Even if it's not a symlink in yours, it doesn't mean it's not systemd.