Linux Process Commands

ps

• By default, it only lists processes attached to the current terminal.
• ps aux list all processes for all users on all terminals
  • a: lists ll user’s processes which are attached to a terminal
  • u: display in user format
  • x: lists all the invoking user’s processes
• f: shows processes in a tree view.

ps aux vs ps -aux

There is a difference between ps aux and ps -aux. ps -aux is the Unix variant and ps aux is the BSD variant. From man ps:

“The POSIX and UNIX standards require that ps -aux print all processes owned by a user named x, as well as printing all processes that would be selected by the -a option. Modern Linux distributions might make ps -aux an alias of ps aux; nevertheless this is intended to be a temporary fix.”

ps -aux should be avoided in favour of ps aux.

pgrep

• pgrep PROCESS outputs the PID of PROCESS.
• -l outputs the name of the PROCESS in addition to the PID.
• -u limits the matches to a user.
• -v inverts the results.

Kill Signals

• There are 64 kill signals.
• kill -l will list all kill signals.

pstree

A nice tree view.