This brief tutorial shows students and new users how to use the ps command on Ubuntu to list and locate currently-running processes.
For example, if you have an application that is locked-up or unresponsive and but gobbling up all your CPU time and/or RAM, you use the ps command to look up the application process and use the kill command to kill it and restore the system to its normal operation.
For students or new users looking for a Linux system to start learning on, the easiest place to start is Ubuntu Linux OS…. It’s a great Linux operating system for beginners.
Ubuntu is an open source Linux operating systems that runs on desktops, laptops, server and other devices…
When learning Ubuntu, you will find that Linux isn’t so different than Windows and other operating systems in so many ways, especially when it comes to using Ubuntu to get work done.…
Both Ubuntu and Windows systems allow you to be productive, easy to use, reliable and enable you to install and run thousands of programs from gaming to productivity suite software for individuals and businesses.
However, when you’re learning to use and understand Ubuntu Linux, you should also learn how to use the command line to terminal. Most Linux users should be able to do some basic command line tasks.
This tutorial is going to show you how….
When you’re ready to learn how to use the ps commands, follow the guide below:
About 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.
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.
The command line options are switches or flags that determined 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 of 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 simple provides you basic options you can use with the ps command|
|–help||Display a help message|
Below are some examples of how to run and use the ps on Ubuntu Linux.
Simply run the ps to invoke it.
Running ps command without options will display a list a 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 name 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, simple run the ps command with the -e or -A option.
This will list all the processes running, but the list is going to be long. So pipe the command with less to break the list by screen.
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, simple run the ps command with the options:
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 list all processes using the full-format use the ps command with the -ef option
ps -ef | less
You should see 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):
sudo kill 33345
To kill a process by name, use the pkill command follow by the process name:
sudo pkill firefox
You can also use the killall command to kill all the process along with its child processes
sudo killall firefox
Congratulations! You have learned how to use the ps command on Ubuntu Linux
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