Question

Give the complete command line to show processes whose PID is 1 or parent PID is 1 in Linux

Answer 1

ps is command to list all process.

command to show process whose PID is 1 is ps -p 1 or ps --pid 1 (you can use any of these)

and command to show process whose parent PID is 1 is ps -ppid 1

I'll illustrate this for you to understand. Even if you have any doubt regarding commands you can always find this by yourself by refering help command.

refer below screenshot:

run

ps --help list

~$ ps --help list Usage: ps [options] Selection by list: -C <command> command name -G, --Group <GID real group id or name -g, --group <group> session or effective group name -p, P, --pid <PID> process id --ppid <PID> parent process id -9, 9, --quick-pid <PID> process id (quick mode) -S, --sid <session> session id -t, t, --tty <tty> terminal -u, U, --user <UID> effective user id or name -U, --User <UID> real user id or name The selection options take as their argument either: a comma-separated list e.g. '-u root, nobody' or a blank-separated list e.g. '-p 123 4567'

so you can see the mark result how to use process id and parent process id.

run ps --pid 1 result attached below

$ ps --pid 1 PID TTY 1 ? TIME CMD 00:00:00 tini

run ps --ppid 1, result attached below

~$ ps --ppid 1 PID TTY 8? TIME CMD 00:00:00 sh

you can always refer ps --help <simple|list|output|threads|misc|all> for more options for this command.

Hope it helps. Please give feedback, if this answer helped resolved your query.

Happy to help you. Keep learning.