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Commands Related to Processes

To see currently running process 
ps
$ps
List the process using most CPU
Top , htop
$top
To stop any process by PID i.e. to kill process
kill    {PID}
$kill  1012
To stop processes by name i.e. to kill process
killall   {Process-name}
pkill
xkill
$killall httpd
To get information about all running process
ps -ag
$ps -ag
To stop all process except your shell
kill 0
$kill 0
For background processing (With &, use to put particular command and program in background)
linux-command  &
$ls / -R | wc -l &
To display the owner of the processes along with the processes  
ps aux
$ps aux
To see if a particular process is running or not. For this purpose you have to use ps command in combination with the grep command

ps ax | grep  process-U-want-to see
For e.g. you want to see whether Apache web server process is running or not then give command
$ ps ax | grep httpd
To see currently running processes and other information like memory and CPU usage with real time updates.
top
$top
Note that to exit from top command press q.
To display a tree of processes
pstree
$pstree
Search  Process id of a process
pgrep
$pgrep firefox
Changing Priority of a process
 nice , renice
$renice 19 PID
Learn More about ps command https://www.journaldev.com/24613/linux-ps-command#viewing-all-the-running-processes-in-different-formats

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