Top Linux Shell Interview Questions and Practical Answers

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

Answer: Use the exit command. Exiting with a non‑zero status (e.g., exit -1) causes the script to terminate with an error.

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

Running the script shows the output before the exit -1 command stops execution.

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

Answer: The sed command can delete the first line of a file. # sed '1 d' file.txt Using the in‑place option -i achieves the same result without redirection:

# sed -i '1 d' file.txt

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

Answer: Combine sed to select the line with wc -c to count characters.

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

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

Answer: Open the file in vi and enable the list option.

vi file.txt
: set list

Note: This also reveals characters such as ^M (carriage return).

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

Answer: Use the sticky bit on the directory.

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

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

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

Waiting – the process is waiting for resources.

Running – the process is actively executing.

Stopped – the process has finished execution or received a kill signal.

Zombie – the process has terminated but remains in the process table.

7. How to use the cut command?

Answer: cut extracts selected columns or characters from a file. # cut -c1-10 txt_linuxmi To extract the 2nd, 5th, and 7th fields separated by semicolons:

# cut -d';' -f2,5,7 txt_linuxmi

8. What is the difference between cmp and diff ?

cmp

compares two files byte by byte and reports the first mismatch. diff shows the changes needed to make the files identical, providing a line‑by‑line difference.

9. Can echo replace ls ?

Answer: Yes, echo * lists the contents of the current directory, producing the same output as ls in many cases.

10. What is an inode?

Answer: An inode is a data structure used by Linux to represent a file; each file has a unique inode number that stores metadata about the file.