PID

In Activity Monitor, find the app in the list and read the PID column. If the column is hidden, choose View > Columns > PID.

In Terminal, pgrep -l Safari lists matching processes with their PIDs. ps -p <PID> -o pid,ppid,comm shows a process's name and its parent's PID.

Every process except the very first has a parent, the process that started it. Choosing View > All Processes, Hierarchically in Activity Monitor shows these parent and child relationships as a tree.

Process names in Terminal can differ from app names. Many apps run helper processes with names like "App Helper (Renderer)", each with its own PID.

1. Open Terminal from Applications > Utilities.
2. Run pgrep -lx Finder to get the PID of a process whose name is exactly Finder. Leave out x to match part of a name.
3. If an app has several processes, run pgrep -lf "Google Chrome" to match against the full command line.
4. To see your own shell's PID, run echo $$.

Error messages and log files often mention a PID without a name. To look it up, run ps -p <PID> -o pid,ppid,user,command. It shows the full path of the program, which user runs it, and the PID of its parent.

In Activity Monitor, click the PID column header to sort by it, then scroll to the number. Double-click the process to open its info window, which also shows its parent process.

If ps prints nothing, the process has already exited.

Check the name first with ps -p <PID>. PIDs are reused, so a number you copied earlier may now belong to a different process.

• kill <PID> asks the process to quit. kill -9 <PID> ends it immediately.
• sample <PID> 5 records what the process is doing for 5 seconds.
• lsof -p <PID> lists the files and network connections it has open.
• lsof -a -p <PID> -d cwd shows the folder it is running in.
• top -pid <PID> shows its live CPU and memory use. Press q to exit.

Commands that work by name, such as killall Safari or pkill Safari, act on every process that matches. By default killall sends the quit signal to all matching processes you own, and pkill matches any process whose name contains the text you type.

That is fine for a single app, but risky when many processes share a name. A browser can run dozens of helper processes, and several copies of node or python may belong to different projects. A PID targets exactly one process, so use it when you want to stop one and leave the rest running.

If you do use a name, preview the matches first. pgrep -l <name> lists what pkill would act on, and killall -d <name> prints what killall would do without sending anything.