Linux Processes - Listing, Inspecting, and Terminating

A Linux process is a running program with a numeric process ID (PID). ps(1) reports that table by reading /proc. Every process has a parent (PPID). Follow PPID far enough and you reach PID 1, the first process in this PID namespace. On a bare-metal or VM host that ancestor is often systemd. Inside a container it is the container entrypoint. The tree still has one root. setsid(1) starts a program in a new session so it is not a child of the interactive shell. kill(1) sends a signal; the default is TERM.

In this lab, you will list processes with ps, record what PID 1 is named, start sleep 4242 with setsid, inspect that process under /proc, and stop it with kill.

Objectives

By completing this beginner lab, you will be able to:

• List processes with ps, ps -e, ps -ef, and ps -eo pid,ppid,comm, then follow PPID until PID 1
• Record the live command name of PID 1 from ps -p 1 -o comm= (container entrypoint, not systemd)
• Start setsid sleep 4242 &, record its PID, and read /proc/PID/comm, /proc/PID/cmdline, and /proc/self
• List signals with kill -l, send TERM with kill PID, and confirm sleep 4242 is gone without trusting a recycled PID

Who is this lab for?

This lab is designed for:

• IT Administrator Foundations learners in Course 1 Stage 2 who can already open a terminal, edit a file in nano, and follow a path under /proc
• Helpdesk and junior sysadmin students who need to find and stop a process before later troubleshooting labs