Finding Out What Processes are Running with ps
Code Listing 9.12. Using ps, you can find out what processes are currently running.
[jdoe@frazz jdoe]$ ps PID TTY TIME CMD 21016 pts/22 00:00:00 bash 21707 pts/22 00:00:00 ps [jdoe@frazz jdoe]$ ps -a PID TTY TIME CMD 21407 pts/3 00:00:00 su 21411 pts/3 00:00:00 bash 21441 pts/3 00:00:00 su 21444 pts/3 00:00:00 bash 19274 pts/11 00:00:05 xterm 23357 pts/12 00:00:04 xterm 13369 pts/5 00:00:00 zsh 23815 pts/9 00:00:00 su 23818 pts/9 00:00:00 bash 23878 pts/9 00:00:00 csh 23942 pts/9 00:00:01 ssh 23972 pts/18 00:00:00 su 23975 pts/18 00:00:00 bash 24103 pts/5 00:00:00 ssh 4658 pts/15 00:00:11 ssh 24318 pts/8 00:00:01 xterm 29188 pts/4 00:00:00 rxvt-2.7.9 29368 pts/4 00:00:00 rxvt 29440 pts/8 00:00:00 vi 23883 pts/20 00:00:02 xterm 27257 pts/16 00:00:01 ssh 6004 pts/20 00:00:00 xterm 20531 pts/20 00:00:02 xterm 21013 pts/22 00:00:00 su 21016 pts/22 00:00:00 bash 21708 pts/22 00:00:00 ps [jdoe@frazz jdoe]$ |
The jobs that we’ve been talking about so far are actually types of processes. Processes are programs, scripts, or commands—including anything you do in the Unix system. All jobs are processes, but not all processes are jobs.
Occasionally, you may want to find out what processes are running on the Unix system. You can do this using ps, as shown in Code Listing 9.12.
To Find Out What Processes are Running with ps:
ps
At the shell prompt, type ps to see the list of the current processes that you’re running in your current shell, including processes for your current shell, as well as any other jobs (Code Listing 9.12). The exact information you see will vary from system to system. In general, though, you’ll find the PID (process identification) number at the far left and the process name at the right.
✓ Tips
You can find out what processes other people are running by typing ps -a at the shell prompt and what processes the system is running (also called daemons) with ps -ax. The ps –ef variant is usually pretty useful for us.
You can sometimes, depending on the system, get a broader look at currently running processes by typing ps –a f. The f flag indicates “forest” view, which lets you see not only the processes, but also how they relate to each other, as shown in Code Listing 9.13.
The results ps offers vary greatly depending on the Unix flavor you’re using. Type man ps at the shell prompt to find out more about your specific ps capabilities.
Code Listing 9.13. The forest view gives you a broader look at running processes.
$ ps –a f PID TTY STAT TIME COMMAND 15043 p0 S 0:00 /bin/login -h calvin raycomm.com -p 15044 p0 S 0:01 \_ -bash 16344 p0 T N 0:00 \_ sh ./slowscript 16345 p0 T N 0:00 | \_ sleep 50 16449 p0 R 0:00 \_ ps f 15911 p1 S 0:00 /bin/login -h calvin raycomm.com -p 15914 p1 S 0:01 \_ -bash 16216 p1 T 0:00 \_ telnet 16217 p1 T 0:00 \_ lynx http://www.raycomm.com/ 16267 p1 T 0:00 \_ man telnet 16268 p1 T 0:00 \_ sh -c (cd /usr/man ; (echo -e ".pl 1100i"; cat / 16269 p1 T 0:00 \_ sh -c (cd /usr/man ; (echo -e ".pl 1100i"; c 16270 p1 T 0:00 \_ sh -c (cd /usr/man ; (echo -e ".pl 1100i 16272 p1 T 0:00 | \_ cat /usr/man/man1/telnet.1 16271 p1 T 0:00 \_ /usr/bin/gtbl 16273 p1 T 0:00 \_ sh -c (cd /usr/man ; (echo -e ".pl 1100i $