A vast majority of Linux systems these days are using systemd – a suite of programs aimed at managing and interconnecting different parts of the system. Systemd started replacing the init process back in 2014 and is now the first process that starts when most Linux systems boot. To get a quick peek, you can run a command like this, which verifies that process 1 is indeed systemd. On this system, two additional systemd processes are currently also running.
$ ps -C systemd
PID TTY TIME CMD
1 ? 00:00:59 systemd <===
1244 ? 00:00:00 systemd
54429 ? 00:00:00 systemd
To see a little more detail, try the command below. The blank within the quotes is meant to prevent related processes like systemd-journald from showing up in the list.
Source:: Network World – Data Center