Guide to Unix/Commands/Process Management

nohup

nohup lets you run a program in a way which makes it ignore hangup signals. This can be used to make a program continue running after a user has logged out. The output of the program is redirected from the standard output to the file nohup.out.

Examples:

$ nohup wget http://foo.org/foo_list.gz
nohup: appending output to `nohup.out'
$

ps

ps displays a list of current processes and their properties.

Examples:

Processes owned by the current user:

$ ps
  PID TTY          TIME CMD
17525 pts/0    00:00:00 su
17528 pts/0    00:00:00 bash
17590 pts/0    00:00:00 ps where pid is process id.

All processes:

$ ps -A

kill

kill is used to send termination signals to processes.

Examples

To send the kill signal to the processes with process id 17525,

$ kill -9 17525

To send the kill signal to all processes,

$ kill -9 -1

see Guide to Unix/Commands/Process Management/Kill

pgrep

pgrep search and kill system processes

Example: Check if apache webserver is running.

$ pgrep -f apache
 5580
 5581
 5582
 5583
 5584
 5585
or
$ svcs -a | grep -i apache.

Stop xterm program with 'pkill' program:

$ pkill -9 xterm

Tips: Display all the process of a user

$ pgrep -l -u arky
894 bash
895 bash
897 bash
898 bash
899 bash
1045 links
1396 startx
1407 xinit
1411 openbox
1412 xterm
1413 xfaces
1414 xsetroot
1415 emacs

pidof

pidof display Process ID (PID) of a task

Example: Display the PID of emacs process:

$ pidof emacs
1415

killall

killall kill a process by name

Example:

Kill the 'xfaces' program:

$ killall xfaces