The command ps produces a list of processes. If the parameter r is added, only processes currently using computing time are shown:
$ ps r PID TTY STAT TIME COMMAND 22163 pts/7 R 0:01 -zsh 3396 pts/3 R 0:03 emacs new-makedoc.txt 20027 pts/7 R 0:25 emacs xml/common/utilities.xml 20974 pts/7 R 0:01 emacs jj.xml 27454 pts/7 R 0:00 ps r
This parameter must be written without a minus sign. The various parameters are written sometimes with and sometimes without the minus sign. The man page could easily frighten off potential users, but fortunately, the ps --help command produces a brief page of help.
To check how many emacs processes are running, use:
$ ps x | grep emacs 1288 ? S 0:07 emacs 3396 pts/3 S 0:04 emacs new-makedoc.txt 3475 ? S 0:03 emacs .Xresources 20027 pts/7 S 0:40 emacs xml/common/utilities.xml 20974 pts/7 S 0:02 emacs jj.xml $ pidof emacs 20974 20027 3475 3396 1288
The parameter -p selects processes via the process ID:
$ ps www -p $(pidof xterm) PID TTY STAT TIME COMMAND 9025 ? S 0:01 xterm -g 100x45+0+200 9176 ? S 0:00 xterm -g 100x45+0+200 29854 ? S 0:21 xterm -g 100x75+20+0 -fn \ -B&H-LucidaTypewriter-Medium-R-Normal-Sans-12-120-75-75-M-70-iso10646-1 4378 ? S 0:01 xterm -bg MistyRose1 -T root -n root -e su -l 25543 ? S 0:02 xterm -g 100x45+0+200 22161 ? R 0:14 xterm -g 100x45+0+200 16832 ? S 0:01 xterm -bg MistyRose1 -T root -n root -e su -l 16912 ? S 0:00 xterm -g 100x45+0+200 17861 ? S 0:00 xterm -bg DarkSeaGreen1 -g 120x45+40+300 19930 ? S 0:13 xterm -bg LightCyan 21686 ? S 0:04 xterm -g 100x45+0+200 -fn \ lucidasanstypewriter-12 23104 ? S 0:00 xterm -g 100x45+0+200 26547 ? S 0:00 xterm -g 100x45+0+200
The process list can be formatted according to your needs. The option -L returns a list of all keywords. Enter the following command to issue a list of all processes sorted by memory usage:
$ ps ax --format pid,rss,cmd --sort rss PID RSS CMD 2 0 [ksoftirqd/0] 3 0 [events/0] 17 0 [kblockd/0] [...] 10164 5260 xterm 31110 5300 xterm 17010 5356 xterm 3896 29292 /usr/X11R6/bin/X -nolisten tcp -br vt7 -auth /var/lib/xdm/authdir/au