Top 10 Linux Shell Interview Questions with Clear Answers

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

Use the exit command. When exit returns a non‑zero status (e.g., exit -1), the script terminates with an error. Example:

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

Running the script shows that everything before exit -1 executes, then the script stops.

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

The sed command removes specific lines. To delete the first line:

# sed '1 d' file.txt

Using the in‑place edit flag -i avoids the need for redirection:

# sed -i '1 d' file.txt

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

Combine sed to select the line and pipe to wc -c to count characters. Example for the 5th line of linuxmi.txt:

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

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

Open the file in vi, enter command mode with :, and run:

set list

This shows characters such as ^M (carriage return).

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

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 idle, awaiting resources.

Running – the process is actively executing.

Stopped – the process has been halted, either after completion or by a 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. Examples:

# cut -c1-10 txt_linuxmi          # first 10 characters of each line
# cut -d';' -f2 -f5 -f7 txt_linuxmi  # fields 2, 5, and 7 using ';' as delimiter

8. What is the difference between cmp and diff ?

cmp

compares two files byte by byte and reports the first mismatch. diff produces a list of changes needed to make the files identical, showing line‑by‑line differences.

9. Can echo replace ls ?

Yes. echo * lists the same filenames that ls would display, though formatting differs.

10. What is an inode?

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