Here is the video version, if you prefer it:
The ps
command is used to display the processes which are currently running. By running ps
without any options, you get the processes associated with the current Terminal, as so:
mislav@mislavovo-racunalo:~/Linux_folder$ ps
PID TTY TIME CMD
10653 pts/1 00:00:00 bash
31210 pts/1 00:00:00 ps
PID
is process ID. TTY
is the controlling terminal associated with the process – this field is irrelevant. TIME
is processor time the process is taking up – the more processor time a process takes up, the more demanding it is. CMD
is the command with which we started the process; it’s the name of the process, with arguments, if arguments exist. (Shotts, 2019)
ps x
gives us all the processes that our current user is running. An example:
mislav@mislavovo-racunalo:~/Linux_folder$ ps x
PID TTY STAT TIME COMMAND
1145 ? Sl 78:18 /usr/bin/gedit --gapplication-service
3350 ? Ss 0:22 /lib/systemd/systemd --user
3351 ? S 0:00 (sd-pam)
3455 ? Ssl 1397:59 /usr/bin/pulseaudio –daemonize=no
...
The new column STAT
is short for state. State is the process state – it indicates what the process is doing. The first capital S
means that process is sleeping, and that means the process is waiting for input. There are other process states, which you can learn more about by typing man ps
and navigating to a section titled PROCESS STATE CODES
.
ps aux
gives us the processes of all users. Its sample output is:
mislav@mislavovo-racunalo:~/Linux_folder$ ps aux
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1 0.0 0.0 170896 5584 ? Ss 2019 26:40 /sbin/init
root 2 0.0 0.0 0 0 ? S 2019 0:01 [kthreadd]
root 3 0.0 0.0 0 0 ? I< 2019 0:00 [rcu_gp]
root 4 0.0 0.0 0 0 ? I< 2019 0:00 [rcu_par_gp]
…
As you can see here, we can see which user started each process (the column USER). We have a couple of additional columns – %CPU
signifies how much CPU (in percentages) the process are using, %MEM
is the percentage of RAM the process are using, VSZ
is the virtual memory size (think of virtual memory as being as large as your hard drive and RAM size combined), RSS
(Resident Set Size) is the amount of RAM the process is using in kilobytes, and START
is the time when the process had started.
This is how you can take a look at the processes running in your computer.
Hope you learned something useful!
References
Shotts, W. (2019). The Linux Command Line, Fifth Internet Edition. Retrieved from http://linuxcommand.org/tlcl.php. Pages 135-137
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