Difference between revisions of "Linux-Ubuntu/C2/Basics-of-System-Administration-in-Linux/English"

Title Slide

Learning Objectives

• Create, modify, switch, and delete Linux user accounts.
• View details of users, groups, and system IDs.
• Monitor disk usage, file and directory sizes, and file system space.
• Use basic Linux commands for system and storage management.

System Requirements

Ubuntu version 24 point zero 4.

Pre-requisites

https://EduPyramids.org

Learners should have Ubuntu version 24 point zero 4.

Admin access or the root permission to execute the commands shown in the tutorial.

For the prerequisite Linux tutorials please visit this website.

Code files

The following code file is required to practice this tutorial.

sa-commands.txt

This file is provided in the Code Files link of this tutorial page.

This file is provided in the Code Files link of this tutorial page.

adduser

We can add user accounts with the help of the sudo command.

sudo

The sudo command has several options.

We will learn these as we progress in this tutorial.

and press Enter.

Type administrator password and press Enter. Highlight message adduser: Only one or two names allowed

In the terminal type sudo space add userand press Enter.

Type the administrator password and press Enter.

The password typed in the terminal is not visible, so type it carefully.

After entering the password, a message sayingOnly one or two names allowed.

Press Enter.Show side by side in files edupyramids.

Type: sudo space adduser space edupyramids and press Enter.

We have now created a new user called edupyramids.

A separate home directory is created automatically during the user creation.

Highlight additional details asking in the terminal.

Type a password of your choice.

I am typing edu p 1 2 3 4 5 as the password and press Enter.

We will be asked to type the new password again.

The password is requested twice for security and confirmation.

The password for the new user is now set.

Press yPress Enter

Let us enter only the Full Name as EduPyramids.

Let’s leave the remaining fields blank by pressing the Enter key.

Finally, to confirm the information type y and press Enter.

This confirms that all the entered details are correct.

For that type: l s space slash home and press Enter.

Here, we can see our newly created user named edupyramids.

The next command we will look at is su.

su command

It is used to switch from the current user to another user account.

Type

su - edupyramids

press enter

Highlight edupyramids@spoken-Inspiron-One- :/$

enter password: edup12345

Type logout

and press enter

At the prompt enter the password for the user edupyramids.

Please recall that the password we had set was edu p 1 2 3 4 5.

Observe that the Terminal shows the new user prompt.

To log out from this user, type logout and press Enter.

The terminal now logs out from the current user, edupyramids.

It returns to the previous user account, spoken.

usermod command

The user mod command lets a superuser modify existing user accounts.

It can lock or disable accounts, manage passwords, and set account expiry dates.

Highlight -e

Type: sudo space usermod space hyphen e space 2026 hyphen 12 hyphen 27 space edupyramids and press Enter.

If prompted, type the admin password.

The user account expiry date is now set using the hyphen e option.

This means the user account edupyramids will be disabled after 27 December 2026.

and press Enter.

The output shows, User I D, Group I D, and the groups to which the current user belongs.

UID

It identifies the user for permissions and ownership.

GID

It is a unique number assigned to a group.

It identifies a group of users for file and directory permissions.

The output shows only the user ID of the current user.

and press Enter.

The output shows the username corresponding to the user ID.

At the terminal, type id space hyphen g and press Enter.

This displays the primary group ID of the current user.

To see all group IDs of the current user,

type: id hyphen capital G and press Enter

You can now see a list of all group IDs associated with the current user.

The userdel command permanently deletes a user account.

The hyphen r option removes the user along with its user’s home directory.

Press Enter to see what happens.

Now, the user edupyramids has been deleted.

To verify this, type:

ls space slash home

and press Enter.

We can see that the user account edupyramids has been deleted.

The hyphen r option removes the home directory as well.

df and du

The d f command displays the available and used disk space.

The d u command shows how much disk space a file or directory occupies.

On the terminal type:

d f space hyphen h

and press Enter.

We see:

• The size of each file system.
• The space used and available.
• The mount points.

The hyphen h option shows the sizes in human-readable format, for easy understanding.

Let me create test files named as test1 test2 test3 in my home directory.

Highlight the summary in the output

Type cd /home/spoken and press Enter.

type: du -s * and press Enter.

Highlight the summary of the sizes shown in the output

type du -ch *press Enter

Highlight the output

d u space hyphen s space asterisk and press Enter.

Option hyphen s gives a summary per file.

This command gives a summary of the sizes of all files in the folder.

Next, type du hyphen c h asterisk press Enter to observe the output.

hyphen c provides a total size.

h makes sizes human-readable.

Summary

In this tutorial we have learnt to:

• Create, modify, switch, and delete Linux user accounts.
• View details of users, groups, and system IDs.
• Monitor disk usage, file and directory sizes, and file system space.
• Use basic Linux commands for system and storage management.

Let us Summarize.

Assignment

As an assignment

1. Create a new user demo and verify the home directory.
2. Switch users using su and logout.
3. Set an expiry date for this user using usermod -e.
4. Check the UID and GID of users
5. Use df -h and du -ch * to check disk usage for practice files.

Thank you