How to See Running Processes in Linux
Use ps to inspect running processes, PIDs, users and commands.
Process inspection is the first step before stopping a program, diagnosing high CPU usage or finding which user owns a service. `ps` gives you a stable snapshot you can pipe into other tools.
Step by step
1 List processes
$ ps auxShows processes for all users with CPU, memory, PID and command information.
2 Find one program
$ ps aux | grep nginxFilters the snapshot for a program name. Verify the result before acting on the PID.
3 Inspect one PID
$ ps -fp 12345Shows a focused row with user, parent PID, start time and command.
4 Show a process tree
$ ps -ef --forestDisplays parent/child relationships, which helps explain how a process was launched.
Tips worth knowing
- `pgrep -af name` is often cleaner than `ps aux | grep name`.
- Use top for a live view rather than repeatedly running ps.
- A PID can be reused, so re-check it before sending signals.
Frequently asked questions
How do I list all running processes?
Use `ps aux` or `ps -ef`.
How do I find a process by name?
Use `pgrep -af name` or filter `ps` output.
How do I see who owns a process?
The user column in `ps aux` shows the process owner.
The commands behind it
See what is running, find a process ID, and combine with grep to hunt down a program.
top & htopThe live dashboard: CPU, memory, load average and the processes consuming them.
killTerminate processes politely or forcibly — and understand what -9 really does.
Concepts involved: Process · PID (Process ID)
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