`pgrep` - list process IDs matching a pattern

pgrep [-f] [-u user] [-l] [-a] [-o] [-n] PATTERN

Options you will use

-l: List the process name as well as the PID.
-a: List the full command line.
-f: Match the full command line.
-o, -n: Only the oldest / newest matching process.
-x, --exact: Match the whole process name exactly (pgrep -x sshd does not match sshd-session).
-f, --full: Match against the full command line, not just the name.
-o, --oldest: Only the oldest matching process.
-n, --newest: Only the newest matching process.
-u, --euid USER: Only processes of this user.
-l, --list-name: Print the name next to the PID.

$ pgrep -o sshd

the parent sshd - useful for oom_score_adj

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