ps

List all processes

$ ps aux

$ ps -u [username]

$ ps -ef --forest

$ ps -p [pid]

$ ps -eo pid,ppid,cmd,%mem,%cpu

$ ps -eLf

ps [options]

ps reports a snapshot of currently running processes on the system. It displays information such as process ID, user, CPU and memory usage, command name, and runtime for each process, providing a point-in-time view of system activity.
The command accepts options in two distinct styles: BSD syntax (without dashes, e.g., aux) and POSIX syntax (with dashes, e.g., -ef). Both produce similar output but differ in column defaults and filtering behavior. The -o option allows fully custom output formats, selecting specific fields like pid, ppid, command, and resource usage.
Common usage patterns include ps aux to list all processes with detailed info, ps -ef --forest to show the process hierarchy as a tree, and ps -p to inspect a specific process by PID.

a

All users.

User-oriented format.

Include processes without tty.

Every process.

Full format.

Select by PID.

Select by user.

Process tree.

Custom output.

BSD and POSIX options differ. Use aux or -ef.

ps is a classic Unix process monitoring utility.

top(1), htop(1), pgrep(1), kill(1)