Working with Text Editors, Package Managers, and SUDO Commands

In this lesson I have covered the essential commands that are widely used for editing text files, managing software packages and handling user priviliges.

Example -:

• Text Editors ( Nano, Vi, Vim )

• Package Management ( Yum, APT )

• The SUDO Command ( for superuser privileges )

1. Text Editors -:

These are used for creating, managing and modifying the text files. Commonly used editors are:

• Nano – Simple and beginner-friendly.

• Vi – A classic Unix text editor.

• Vim – An improved version of Vi.

In order to use these editors we need to install them. Let's check how to do it.

Run the following commands: to check if they already installed or not .

a -: nano --version b -: vi --version c -: vim --version

If any editor is missing, install it using:

• sudo yum install nano -y # For RHEL-based Linux (Amazon Linux 2)

  

in my case it was already installed, so it did not run anything else.

• sudo apt install nano -y # For Debian-based Linux (Ubuntu)

Nano Text Editor

Nano is the easiest text editor to use.

Opening a File in Nano :

Run Command --> nano index.html

Editing and Saving in Nano

• Modify the file directly.

• Save changes: CTRL + O, then Enter

• Exit Nano: CTRL + X

Example: Editing a Static Website Title

1. Open index.html in Nano.

   

2. Modify the title tag.

3. Save changes using CTRL + O, then press Enter.

4. Exit Nano using CTRL + X.

   

To verify the change, refresh the website in the browser*.*

Vi Text Editor

Vi is a traditional Unix text editor. It operates in two modes:

1. Insert Mode – For text editing, press(i key).

2. Command Mode – For executing commands (Esc key to switch back).

Opening a File in VI

Run command --> vi index.html

Editing in Vi

• Enter Insert Mode: Press i

• Modify the file.

• Exit Insert Mode: Press Esc

• Save and exit: Type :wq then Enter

• Exit without saving: Type :q! then Enter

To check if the changes are applied, refresh the website in the browser.

Vim Text Editor

Vim is an advanced version of Vi with additional features.

Opening a File in Vim

Run command --> vim index.html

Vim works similarly to Vi, with Insert Mode (i to enter) and Command Mode (Esc to exit).

• Modify the title tag.

• Press Esc, then type :wq to save and exit.

After making changes, refresh the website in the browser to verify the update.

2. Package Management -:

In Linux, Package managers are responsible to manage the software and allows to install, update and remove software packages efficiently.

Each Linux distribution uses a specific package manager:

• YUM – For RHEL-based distributions (Amazon Linux 2, CentOS).

• APT – For Debian-based distributions (Ubuntu, Debian).

In the below screen shots, I have used the YUM package manager because I have used Amazon Linux 2.

1. Updating the System: Run command -- > Sudo yum update -y

   

2. Installing a Package

let's install ( Nano ): Run command -- > Sudo yum install nano -y

3. Removing a Package: Run command -- > Sudo yum remove nano -y

3. The Sudo Command

In Linux we cannot run some commands as a Root user, so for that we need to get privileges as a Superuser, we use { SUDO }.

Example :

Run command: sudo yum install nginx -y

If a user does not have sudo access, Linux denies permission

4. Managing user priviliges with Sudo

In Linux, there is file which is called { SUDOERS file } which shows the users who have administrative rights.

Checking If a User Has Sudo Access

Run command --> id

If the output contains: ---->> groups=1000(ec2-user), 27(wheel)

It means the user belongs to the { wheel group }, which has sudo privileges.

5. Editing the Sudoers File Safely

To modify user permissions, use visudo:

Run command: -- > sudo visudo

Locate: -- > %wheel ALL=(ALL) ALL

if the users are in the wheel group then it means it can execute all commands as a root user.

6. Adding a User to the Sudo Group

To grant full root privileges, add the user in the sudoers file:

ec2-user ALL=(ALL) ALL

Save and exit (Esc, then :wq).

7. Verifying Sudo Privileges

To confirm a user's sudo access:

Run Command -- > sudo -l

This lists all commands the user can execute as a superuser.

TROUBLESHOOT -:

While installing NGINX server i faced following problem -:

Not able to start my NGINX server :

Even after running { sudo yum install nginx } and { sudo systemctl enable nginx } , if it is not running then use this command -:

a. Run command -: sudo nginx -t

This command will test your Nginx configuration for syntax errors and ensure all file paths and directives are correct.

If your configuration is correct, you will see an output indicating that the syntax is okay and the test was successful:

nginx: the configuration file /etc/nginx/nginx.conf syntax is ok

nginx: the configuration file /etc/ngin/nginx.conf test is successful