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
 310455 ?        00:00:00 php-cgi
 310586 ?        00:00:00 php-cgi
 310624 ?        00:00:00 bash
 310634 ?        00:00:00 ps
% ps -H
    PID TTY          TIME CMD
 310586 ?        00:00:00 php-cgi
 310455 ?        00:00:00 php-cgi
 310624 ?        00:00:00   bash
 310650 ?        00:00:00     ps
% ps -Hf
UID          PID    PPID  C STIME TTY          TIME CMD
cs155     310586 4020091  0 15:46 ?        00:00:00 /usr/bin/php-cgi
cs155     310455 4019223  0 15:46 ?        00:00:00 /usr/bin/php-cgi
cs155     310624  310455  0 15:46 ?        00:00:00   bash /tmp/pmwiki-bash-scriptFa8OUo
cs155     310665  310624  0 15:46 ?        00:00:00     ps -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

CS155: Introduction to Unix

Spring 2018

Processes

Processes

Job Control

Listing Processes

Job priority