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Processes

CS155 Processes

Job Control

• Unix allows us to multi-task. This means we can run more than one program at the same time.
• Ctrl-C kills the current program.
• There are ways to run programs in the background (control-Z, &, fg, bg, kill) but, these days, we usually just create another terminal window.

Listing Processes

% ps
  PID TTY          TIME CMD
14314 pts/0    00:00:00 bash
14326 pts/0    00:00:00 ps
% ps -H
  PID TTY          TIME CMD
14314 pts/0    00:00:00 bash
14327 pts/0    00:00:00   ps
% ps -Hf
UID        PID  PPID  C STIME TTY          TIME CMD
neutron  14314 14313  0 15:57 pts/0    00:00:00 -bash
neutron  14328 14314  0 15:58 pts/0    00:00:00   ps -H -Hf

ps – list my running processes

• -f : give more information
• -e : list processes for everyone, not just this terminal
• -H : hierarchical (indented) output

Job priority

• All processes have a priority which determines the order in which they are granted cpu time.
• System processes have the highest priority.
• The command nice can be used to change the priority of your process.
• nice my_prog