Madhurig: Madhurig moved page Linux-Ubuntu/C2/Working-with-Linux-Processes/English to Linux-New/C2/Working-with-Linux-Processes/English

2026-03-24T11:08:35Z

Madhurig moved page Linux-Ubuntu/C2/Working-with-Linux-Processes/English to Linux-New/C2/Working-with-Linux-Processes/English

Madhurig at 10:31, 11 March 2026

2026-03-11T10:31:53Z

Madhurig at 10:26, 11 March 2026

2026-03-11T10:26:43Z

Madhurig: Created page with "'''TITLE: Working with Linux Processes''' '''Author:''' EduPyramids '''Keywords:''' Process, shell process, PID, PPID, spawning, ps, parent, child, subshell, system process..."

2026-01-24T18:03:05Z

Created page with "'''TITLE: Working with Linux Processes''' '''Author:''' EduPyramids '''Keywords:''' Process, shell process, PID, PPID, spawning, ps, parent, child, subshell, system process..."

New page

'''TITLE: Working with Linux Processes'''

'''Author:''' EduPyramids

'''Keywords:''' Process, shell process, PID, PPID, spawning, ps, parent, child, subshell, system process, init

{| border=1
|-
|| '''Visual Cue'''
|| '''Narration'''
|-
|| Slide 1

'''Title Slide'''
|| Welcome to this spoken tutorial on '''Working with Linux Processes'''.
|-
|| '''Slide 2'''

''' Learning Objectives '''
|| In this tutorial, we will learn about:
* Processes in Linux
* Parent and child processes
* Process creation and termination
* Process attributes like '''PID''' and '''PPID'''
* The '''ps''' command and its options

|-
|| '''Slide 3'''

'''System Requirements'''
|| To record this tutorial, I am using,

'''Ubuntu OS '''version 24 point zero 4
|-
|| '''Slide 4'''

'''Pre-requisites'''

'''https://EduPyramids.org'''

|| To follow this tutorial,

Learners should have '''Ubuntu '''version 24 point zero 4.

For the prerequisite Linux tutorials please visit this website.
|-
|| '''Slide 5'''

'''Code Files'''

The following code file is required to practice this tutorial

# '''wlp-commands.txt'''

This file is provided in the Code Files link of this tutorial page.
|| The following code file is required to practice this tutorial.

This file is provided in the '''Code Files''' link of this tutorial page.
|-
|| '''Slide 6'''

'''What is a Process ?'''

'''processing.png'''
|| Anything running in Linux is called a '''process'''.

The '''shell''' that accepts commands is a process.

Commands typed in the terminal become processes when executed.

For example, video players, web browsers, and running shell scripts are also processes.
|-
|| '''Slide 7'''

'''What is a Shell?'''

'''Shell1.png '''
|| The '''shell''' accepts user commands and acts as an interface to the '''Linux kernel'''.

It runs commands and shows output.

The kernel starts the shell at login.

The '''shell''' creates processes for terminal commands.
|-
|| Open a terminal.

Press Ctrl + Alt + T keys.
|| Let us open a '''terminal'''.
|-
|| Highlight to '''$ '''sign
|| Here, we can see the command prompt as a '''dollar''' '''sign'''.

Displaying this prompt is the job of the '''shell process'''.
|-
|| Type '''date '''press '''Enter'''

Highlight '''Date'''.

Highlight '''Output.'''
|| Now let us type '''date''' and press '''Enter'''.

As soon as we do this, the shell process creates a new process called '''date.

'''The shell creates the '''date''' process, so it is called the '''parent process.'''

The '''date''' is called its '''child process'''.

After displaying the system date and time, the '''date process''' ends.
|-
|| '''Slide 8'''

'''Spawning'''
|| A shell can start another shell as a separate process.

Starting a new process is called '''spawning''' a process.
|-
|| Type '''sh '''and press '''Enter'''.
|| To '''spawn''' another shell process, go to the terminal, type''' s h''', and press '''Enter'''.
|-
|| Highlight $
|| The original shell, called shell one, creates a child shell.

We can call this child shell as a subshell, or shell two.
|-
|| Type l s and press enter
|| Let us run the''' l s''' command in this new shell.

We see a list of files and directories as output.

At this moment, a new process named ls is created.
|-
|| Highlight '''$ of ls'''Highlight '''$ of sh'''
|| Here, '''Shell 2''' is the '''parent''' of the''' l s''' process.

'''Shell 1''' is the '''grandparent''' of the''' l s '''process.

The '''l s''' process is the '''child '''of '''Shell 2'''.

At the same time, '''Shell 2''' is the '''child''' of '''Shell 1'''.
|-
|| Type '''exit '''press '''Enter'''.

|| To terminate Shell 2, type '''exit''' and press '''Enter'''.

This terminates Shell 2, returning us to the original command prompt of Shell 1.
|-
||
|| Now Let’s learn about '''P I D''' and '''P P I Ds'''
|-
|| '''Slide 9'''

'''PID''' and '''PPID'''

'''parent-child.png'''
|| Just as a person has a name or ID, each Linux process has its own attributes.

The key process attributes are '''P I D''' (Process ID) and '''P P I D''' (Parent Process ID).

These details are stored by the Linux kernel in the '''process table'''.

'''PID''' (Process ID) is a unique number assigned to each process by the kernel.

'''PPID''' (Parent Process ID) is the '''PID''' of the process that created (spawned) it.
|-
|| '''Type: clear '''and press '''Enter.'''
|| Let me clear the terminal screen
|-
|| Type '''echo $$'''

press '''Enter'''

point mouse to output '''PID''' number.

|| To see the '''PID''' of the current shell, in a terminal type '''echo space dollar dollar '''and press '''Enter'''.

A number is displayed.

This number is the '''PID''' of the current shell.
|-
|| Type''' ps '''press''' Enter'''
|| Now type '''p s''', it stands for '''process status'''.Press '''Enter''' to see the output.

It shows the processes currently running.

A list of all the processes owned by the current user.
|-
|| hover mouse over '''CMD''' column

hover mouse over '''PID''' column

hover mouse over '''TTY''' column

hover mouse over '''TIME''' columnHighlight previous commands output PID number

|| In the output of the''' p s''' command, we can see the following:

Name of the process under the '''C M D''' column.

'''P I D''' of the process.

'''TTY''' shows the terminal or console linked to the process.

'''TIME''' shows the total CPU time used by the process.

The '''P I D''' of the shell matches the number shown by '''echo dollar dollar '''command.
|-
|| point mouse to PID of bash and output of echo $$ command
|| On my machine, running '''ps '''shows two processes:

* bash, which is the shell itself, and
* ps, the command we just ran.

|-
|| type '''sh''' press enter
|| Let us see what happens if we '''spawn '''a subshell.

Type '''s h '''and press '''Enter.'''
|-
|| Type '''ps''' press enter

Highlight '''bash, sh, ps '''highlight all the '''PID '''number.

|| Now, in the new prompt that appears on the next line, type '''p s '''and press '''Enter'''.

We can now see three processes:
* '''bash''' the original shell
* '''s h''' the subshell we just '''spawned'''
* '''p s''' the command itself

Notice that the '''bash PID '''remains the same.The '''p s''' command has many options.
|-
|| type '''ps -f '''press Enter

Show the output Highlight '''bash, sh,''' and '''ps -f'''.

|| Now type '''p s space''' '''hyphen''' '''f''' and press '''Enter.'''

This lists three processes again: '''bash, s h,''' and '''p s hyphen f'''.
|-
|| point your mouse to '''UID''', '''PPID''' and '''PID''' fields
|| The only difference with '''p s hyphen f '''is that it shows more process attributes.

* '''U I D''' shows the user who started the process.
* '''P P I D''' shows the '''P I D''' of the '''parent process'''.

|-
|| point your mouse to the '''PID''' of '''bash''' and '''PPID''' of '''sh'''
|| For example, bash is the '''parent''' of the '''s h''' subshell.

Therefore, the '''P I D '''of''' bash''' is the same as the '''P P I D '''of''' s h'''.
|-
|| point your mouse to '''PID''' of '''sh''' and '''PPID''' of '''ps -f '''

'''Highlight C column, '''
|| The '''s h '''process is the parent of the '''p s''' command we just ran.

The '''PID''' of '''s h''' matches the '''P P I D''' of '''p s''' in the '''p s hyphen f '''output.

The '''C''' column shows the '''CPU''' usage percentage over the process lifetime.

In this example, it is 0 due to minimal '''CPU''' usage.
|-
|| point your mouse to '''STIME'''
|| The '''STIME''' field shows the time when the process started.

The other fields are the same as those displayed earlier by '''p s'''.

|-
|| '''Slide 10 '''

'''Linux Processes'''

process.png'''
|| In Linux processes are of two types:

# '''User processes''' – These are started by users.

For example,''' p s '''or most commands we run in the terminal.

# '''System processes''' – These are started by the system, often during system startup or user login.

For example, '''bash''' is a system process.
|-
||
|| To view all processes, including system processes, use the '''p s''' command with '''hyphen e''' or '''hyphen A'''.
|-
|| type''' ps -e'''

Press '''enter'''

|| Go to the terminal and type '''ps space hyphen e'''

and press '''Enter'''.

We can see a large list of processes.
|-
|| type

'''ps -e | more'''

press '''Enter'''
|| To get a multipage display type '''ps space hyphen e space vertical bar space more'''

and press '''Enter'''.
|-
|| Highlight: First line of output:- '''1 ? 00:00:08 systemd'''
|| As seen earlier, the '''more''' command shows only the processes that fit in one screen.

Press '''Enter''' and scroll through the rest of the process list.The first process in this list is particularly interesting.

It is called the '''init process'''.

Almost all other processes are '''spawned '''from''' init''', and it always has a '''P I D '''of''' 1'''.
|-
|| Press '''q'''

Type '''exit'''

Press '''Enter'''

Highlight the '''original prompt'''
|| Press '''q''' to come back to the prompt.

Type '''exit''' and press '''Enter''' to leave the shell and return to the original prompt.
|-
|| '''Slide 11'''

'''Summary'''

In this tutorial, we have learnt about:

* Processes in Linux
* Parent and child processes
* Process creation and termination
* Process attributes like PID and PPID
* The ps command and its options

|| With this we come to the end of this tutorial.

Let us summarise.

|-
|| '''Slide 12'''

As an assignment,

Run the following commands and check the output.

ps -ef

ps -eF

ps -ely

ps -c
|| As an assignment, please do the following.

|-
|| '''Slide 13'''

'''Thank you'''
|| This Spoken Tutorial is brought to you by EduPyramids Educational Services Private Limited, SINE, IIT Bombay.

Thank you.
|-
|}

← Older revision	Revision as of 11:08, 24 March 2026
(No difference)

@@ Line 33: / Line 33: @@
 || To record this tutorial, I am using,
- '''Ubuntu OS '''version 24 point zero 4
+'''Ubuntu OS '''version 24 point zero 4
 |-
 || '''Slide 4'''
@@ Line 41: / Line 41: @@
 '''https://EduPyramids.org'''
- || To follow this tutorial,
+|| To follow this tutorial,
 Learners should have '''Ubuntu '''version 24 point zero 4.

@@ Line 147: / Line 147: @@
 |-
 || Type '''exit '''press '''Enter'''.
 || To terminate Shell 2, type '''exit''' and press '''Enter'''.
@@ Line 155: / Line 152: @@
 |-
 ||
-|| Now Let’s learn about '''P I D''' and '''P P I Ds'''
+|| Now Let’s learn about '''P I D''' process Id and '''P P I D parent process ID'''
-|-
-|| '''Slide 9'''
-−
-'''PID''' and '''PPID'''
-−
-'''parent-child.png'''
-|| Just as a person has a name or ID, each Linux process has its own attributes.
-−
-The key process attributes are '''P I D''' (Process ID) and '''P P I D''' (Parent Process ID).
-−
-These details are stored by the Linux kernel in the '''process table'''.
-−
-'''PID''' (Process ID) is a unique number assigned to each process by the kernel.
-−
-'''PPID''' (Parent Process ID) is the '''PID''' of the process that created (spawned) it.
 |-
 || '''Type: clear '''and press '''Enter.'''
@@ Line 277: / Line 261: @@
 |-
-|| '''Slide 10 '''
-−
-'''Linux Processes'''
-−
-process.png'''
-|| In Linux processes are of two types:
-−
-# '''User processes''' – These are started by users.
-−
-For example,''' p s '''or most commands we run in the terminal.
-−
-# '''System processes''' – These are started by the system, often during system startup or user login.
-−
-For example, '''bash''' is a system process.
-|-
-||
-|| To view all processes, including system processes, use the '''p s''' command with '''hyphen e''' or '''hyphen A'''.
-|-
 || type''' ps -e'''
 Press '''enter'''
-|| Go to the terminal and type '''ps space hyphen e'''
+||Type '''ps space hyphen e'''
 and  press '''Enter'''.
@@ Line 372: / Line 339: @@
 '''Thank you'''
-|| This Spoken Tutorial is brought to you by EduPyramids Educational Services Private Limited, SINE, IIT Bombay.
 Thank you.
 |-
 |}

Linux-New/C2/Working-with-Linux-Processes/English - Revision history

Madhurig: Madhurig moved page Linux-Ubuntu/C2/Working-with-Linux-Processes/English to Linux-New/C2/Working-with-Linux-Processes/English

Madhurig at 10:31, 11 March 2026

Madhurig at 10:26, 11 March 2026

Madhurig: Created page with "'''TITLE: Working with Linux Processes''' '''Author:''' EduPyramids '''Keywords:''' Process, shell process, PID, PPID, spawning, ps, parent, child, subshell, system process..."