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See this page as a slide show

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
1827711 ?        00:00:00 php-cgi
1827712 ?        00:00:00 bash
1827714 ?        00:00:00 ps
% ps -H
    PID TTY          TIME CMD
1827711 ?        00:00:00 php-cgi
1827712 ?        00:00:00   bash
1827716 ?        00:00:00     ps
% ps -Hf
UID          PID    PPID  C STIME TTY          TIME CMD
cs155    1827711 2809789  0 13:31 ?        00:00:00 /usr/bin/php-cgi
cs155    1827712 1827711  0 13:31 ?        00:00:00   bash /tmp/pmwiki-bash-scriptCok9VI
cs155    1827718 1827712  0 13:31 ?        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

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