How to Find a Process Name by Its PID in Linux

Sometimes you need to quickly figure out which process is running under a specific PID. In this guide, we’ll show you how to do that — but first, let’s briefly go over how processes work in Linux. Whenever you or the system launches a program, the Linux kernel creates a separate process for it. This process holds all the information about the program’s execution: variables, input/output, state, and more.

Since Linux is a multitasking system, it runs many processes at once. To keep things organized, each process is assigned a unique number — the PID (Process ID). Without it, managing tasks would be a mess.

Information about processes is stored in the /proc directory. Each running process has its own folder named after its PID.

How to View the Contents of /proc

You can simply use the ls command to look inside /proc:

ls /proc

If the list is too long, it helps to pipe it through less:

ls /proc | less

The numbered folders represent running processes. The names of those folders are their PIDs.

How to View the Contents of a Specific Process

For example, the systemd process, which launches the system, always has PID 1. To see what’s inside its folder:

ls /proc/1

How to Monitor Running Processes

To check which processes are running and what their PIDs are, use standard tools:

→ ps aux — lists all processes along with their PIDs.

→ top — opens an interactive view of active processes, updating in real time.

→ glances — a modern monitoring tool that shows CPU, memory, disk usage, and more in a user-friendly way.

How to Get the PID by Process Name

If you know the name of a program, you can find its PID with pidof:

pidof firefox
pidof python
pidof cinnamon

How to Get the Process Name by PID

Now for the main part — say you already have a PID and want to know what process it refers to. Use this command:

ps -p PID -o comm=

Examples:

ps -p 2523 -o comm=
ps -p 2295 -o comm=

Here:
→ -p specifies the PID.

→ -o comm= tells ps to output only the command name (i.e., the process name).

More Info

To explore more options with ps, check its manual:

man ps