Top 10 Linux Shell Interview Questions with Clear Answers

This guide answers ten frequently asked Linux shell interview questions, providing concrete command examples and explanations.

1. How to abort a shell script before it finishes?

Use the exit command with a non‑zero status. For example, placing exit -1 in the script will cause it to terminate with an error.

#!/bin/bash

echo "Hello"
exit -1

echo "bye"

Running the script shows the error message and the subsequent echo "bye" still executes because the typo exit-1 is not recognized.

2. How to remove the header line of a file?

The sed command can delete the first line. To save the result, redirect the output or use the -i in‑place option.

# sed '1d' file.txt > new_file.txt
# sed -i '1d' file.txt

3. How to check the length of a specific line in a text file?

Combine sed to print the line and pipe to wc -c to count characters.

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

4. How to display all non‑printable characters in a file?

Open the file in vi, enter command mode, and execute set list. This reveals characters such as ^M.

5. How to create a shared directory where members can create files but only the owner can delete them?

Use the sticky bit and group write/execute permissions:

# mkdir dir_xyz
# chmod g+wx dir_xyz
# chmod +t dir_xyz

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

6. What are the main stages of a Linux process lifecycle?

Waiting : The process is waiting for resources.

Running : The process is actively executing.

Stopped : The process has been halted or received a kill signal.

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

7. How to use the cut command?

cut

extracts specific columns or character ranges from a file.

# cut -c1-10 txt_linuxmi          # first 10 characters
# cut -d';' -f2,5,7 txt_linuxmi   # fields 2, 5, and 7 using ';' as delimiter

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. Can echo replace ls ?

Yes, echo * lists directory contents similarly to ls, though formatting differs.

10. What is an inode?

An inode is a data structure on a Unix/Linux filesystem that stores metadata about a file, including a unique inode number.