Top 10 Linux Shell Interview Questions and Practical Answers

1. Interrupting a Shell Script

Use the exit command with a non‑zero status to stop a script. For example, exit -1 forces an error and terminates execution.

Example script:

#!/bin/bash
 echo "Hello"
 exit -1
 echo "bye"

Running sh linuxmi.sh produces:

Hello
linuxmi.sh: line 3: exit-1: command not found
bye

2. Removing the First Line of a File

The sed command can delete the header line:

sed '1 d' file.txt

To save the result, redirect the output:

sed '1 d' file.txt > new_file.txt

Or edit the file in place with the -i option:

sed -i '1 d' file.txt

3. Checking the Length of a Specific Line

Combine sed with wc -c to count characters:

sed -n '5 p' linuxmi.txt | wc -c

4. Viewing All Non‑Printable Characters

Open a file in vi, enter command mode with Esc then :, and run:

set list

This displays characters such as ^M for carriage returns.

5. Directory Permissions for Group Collaboration

Create the directory and set group write/execute and the sticky bit so only owners can delete files:

mkdir dir_xyz
chmod g+wx dir_xyz
chmod +t dir_xyz

The sticky bit ( +t) ensures that only the file owner, directory owner, or root can remove files.

6. Linux Process Lifecycle

Waiting : Process is waiting for resources.

Running : Process is actively executing.

Stopped : Process has been halted or killed.

Zombie : Process has terminated but remains in the process table.

7. Using the cut Command

Extract the first 10 characters of a file:

cut -c1-10 txt_linuxmi

Extract specific columns (e.g., 2, 5, and 7) using a delimiter:

cut -d';' -f2 -f5 -f7 txt_linuxmi

8. Difference Between cmp and diff

diff

shows the changes needed to make two files identical, while cmp compares files byte‑by‑byte and reports the first mismatch.

9. Replacing ls with echo

Listing directory contents can be mimicked by echo *, which outputs the same file names as ls.

10. What Is an Inode?

An inode is a data structure used by Linux to store metadata about a file, including a unique inode number that identifies the file within the filesystem.