Unix Tools - Linux Command Related with Process

Following tables most commonly used command(s) with process:

For this purpose	Use this Command	Examples*
To see currently running process	ps	$ ps
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}	$ 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 See the output of top command.	$ top Note that to exit from top command press q.
To display a tree of processes	pstree	$ pstree

* To run some of this command you need to be root or equivalnt user.
NOTE that you can only kill process which are created by yourself. A Administrator can almost kill 95-98% process. But some process can not be killed, such as VDU Process.
Exercise:
You are working on your Linux workstation (might be learning LSST or some other work like sending mails, typing letter), while doing this work you have started to play MP3 files on your workstation. Regarding this situation, answer the following question:
1) Is it example of Multitasking?
2) How you will you find out the both running process (MP3 Playing & Letter typing)?
3) "Currently only two Process are running in your Linux/PC environment", Is it True or False?, And how you will verify this?
4) You don't want to listen music (MP3 Files) but want to continue with other work on PC, you will take any of the following action:

1. Turn off Speakers
2. Turn off Computer / Shutdown Linux Os
3. Kill the MP3 playing process
4. None of the above