The ps Command
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The ps command displays information about active processes. It lists all running processes by default but additional switches provide more details. Common switches include -A for a complete list, -f for full details, and -l for a long listing. The ps command is often used to find the process ID (PID) of a frozen process so it can be killed using the kill command. Piping ps output to grep can filter results to quickly find a specific process.
The ps Command
- 1. The ps command Kevin O'Brien Washtenaw Linux Users Group http://www.lugwash.org
- 2. What is ps? ● ps stands for Process Status ● Gives a list of all processes 2
- 3. Usage ● Type “ps” at the prompt, and you get very little ● Switches are key, as always ● To get a complete list, for instance, type “ps -A” (Note: Linux is case-sensitive) ● Also, “ps -e” will give a complete list 3
- 4. Other switches you might want ● -f give a full listing, i.e. more information about each process listed ● -u username will list all processes running by a specific user ● -l gives a long listing. This is even more data than in a full listing 4
- 5. Combining switches ● You can use more than one switch at a time ● Example: “ps -el” would give you a long listing of all of your processes ● Example: “ps -el -u username” would give you a long listing of all processes owned by a certain username 5
- 6. Common use ● The most common reason to use ps is the get the process ID for a process that is out of control ● With the process ID you can use the kill command (e.g. “kill 6985” would kill whichever process had that process ID) 6
- 7. Piping ● Sometimes, the list of processes can be long ● If you only need to get a process ID, try piping to grep ● Example: Firefox is frozen and I need to kill it ● “ps -e | grep firefox” would return one line with the process for Firefox ● I can then easily enter the kill command 7