This brief tutorial shows students and new users how to use the ps command on Ubuntu to list and locate currently running processes.
The ps command is very useful in Ubuntu Linux. It allows you to view details of the currently running processes on your system and helps you to identify any processes that might be causing issues.
You can use the ps command to kill or terminate processes that are not behaving normally or are gobbling up all your CPU time and RAM. This can help restore the system’s regular operation and prevent any damage to your system.
Additionally, the ps command provides various options that allow you to customize the output and display detailed information about the processes.
The PS command is essential for managing and troubleshooting processes on Ubuntu Linux.
About the ps command:
The ps command is a command line utility that helps you view details of currently running processes with options to kill or terminate processes that are not behaving normally.
Syntax:
The syntax is the rule and format of how the ps command can be used. These syntax options can be reordered, but a straight format must be followed.,.
Below is an example syntax of how to use the ps command.
ps [options]
Options:
The command line options are switches or flags that determine how the commands are executed or controlled. They modify the behavior of the commands. They are separated by spaces and followed after the commands.
Below are some options for the ps command:
| options | Replace command a command you want to look up |
| ps –help list | ps –help list command option common options you can use with the ps command |
| ps –help all | ps –help all command option gives you all the possible command options you can use with ps |
| ps –help misc | ps –help misc gives you miscellaneous options you can use with the ps command |
| ps –help simple | ps –help simply provides you basic options you can use with the ps command |
| –help | Display a help message |
Examples:
Below are some examples of how to run and use the ps on Ubuntu Linux.
Simply run the ps to invoke it.
Running the ps command without options will display a list of processes started by the account running the command.
Output: PID TTY TIME CMD 2658 pts/0 00:00:00 bash 19229 pts/0 00:00:00 ps
These represent the columns.
- PID: The process ID number of the running process.
- TTY: The console names the user is logged in at.
- TIME: The CPU processing time used by the process.
- CMD: The command name that started the process
For example, if you want to list all processes currently running on the system, even those started by other users, simply run the ps command with the -e or -A option.
Example:
ps -e
This will list all the processes that are running but will be extended. So, pipe the command with less to break the list by the screen.
Example:
ps -e | less
You should see something similar to the list below:
Output:
PID TTY TIME CMD
1 ? 00:00:03 systemd
2 ? 00:00:00 kthreadd
3 ? 00:00:00 rcu_gp
4 ? 00:00:00 rcu_par_gp
6 ? 00:00:00 kworker/0:0H-kb
7 ? 00:00:00 kworker/u4:0-ev
8 ? 00:00:00 mm_percpu_wq
9 ? 00:00:00 ksoftirqd/0
10 ? 00:00:00 rcu_sched
11 ? 00:00:00 migration/0
12 ? 00:00:00 idle_inject/0
14 ? 00:00:00 cpuhp/0
15 ? 00:00:00 cpuhp/1
When you want to know more details of running processes, including displaying their parent processes, simply run the ps command with the options:
Example:
ps -eH | less
This will display processes along with their parents
Output: 2095 ? 00:00:00 gdm-session-wor 2119 tty2 00:00:00 gdm-x-session 2121 tty2 00:00:20 Xorg 2130 tty2 00:00:00 gnome-session-b 2267 ? 00:00:00 ssh-agent 2300 tty2 00:00:46 gnome-shell 2334 tty2 00:00:00 ibus-daemon 2338 tty2 00:00:00 ibus-dconf 2599 tty2 00:00:00 ibus-engine-sim 2416 tty2 00:00:00 gsd-power
This lists all processes using the full-format use the ps command with the -ef option
Example:
ps -ef | less
You should see a similar list as shown below:
Output: UID PID PPID C STIME TTY TIME CMD root 1 0 0 12:07 ? 00:00:03 /sbin/init splash root 2 0 0 12:07 ? 00:00:00 [kthreadd] root 3 2 0 12:07 ? 00:00:00 [rcu_gp] root 4 2 0 12:07 ? 00:00:00 [rcu_par_gp] root 6 2 0 12:07 ? 00:00:00 [kworker/0:0H-kb] root 7 2 0 12:07 ? 00:00:00 [kworker/u4:0-ev] root 8 2 0 12:07 ? 00:00:00 [mm_percpu_wq] root 9 2 0 12:07 ? 00:00:00 [ksoftirqd/0] root 10 2 0 12:07 ? 00:00:00 [rcu_sched] root 11 2 0 12:07 ? 00:00:00 [migration/0] root 12 2 0 12:07 ? 00:00:00 [idle_inject/0] root 14 2 0 12:07 ? 00:00:00 [cpuhp/0] root 15 2 0 12:07 ? 00:00:00 [cpuhp/1] root 16 2 0 12:07 ? 00:00:00 [idle_inject/1]
These represent the column:
- UID: The process owner user ID.
- PID: The process ID.
- PPID: Parent process ID.
- C: The number of children the process has.
- STIME: Start time of the process.
- TTY: The console name of the user who started.
- TIME: The CPU processing time used.
- CMD: The command name or process name
Killing a process
To kill a process, simply run the kill followed by the process ID ( PID):
Example:
sudo kill 33345
To kill a process by name, use the kill command followed by the process name:
Example:
sudo pkill firefox
You can also use the killall command to kill all the processes along with their child processes
sudo killall firefox
That’s it!
Congratulations! You have learned how to use the ps command on Ubuntu Linux.
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