Top 10 Linux Shell Interview Questions and How to Solve Them

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

Use the exit command with a non‑zero status; for example, exit -1 forces the script to terminate with an error.

Example script linuxmi.sh:

#!/bin/bash

echo "Hello"
exit-1

echo "bye"

Running sh linuxmi.sh produces:

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

The typo exit-1 is not a valid command, so the script continues after reporting the error.

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

The sed command can delete specific lines. To drop the first line: sed '1 d' file.txt To save the result back to a file, redirect the output: sed '1 d' file.txt > new_file.txt Alternatively, use the in‑place edit flag:

sed -i '1 d' file.txt

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

Combine sed with wc -c to count characters. For example, to get the length of line 5 in linuxmi.txt:

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

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

Open the file with vi, enter command mode, and run: set list This shows characters such as ^M (Ctrl+M) and other invisible symbols.

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

Use a sticky bit on the directory:

mkdir dir_xyz
chmod g+wx dir_xyz
chmod +t dir_xyz

The sticky bit ( +t) ensures that only the file’s owner, the directory’s owner, or root can delete files within the directory.

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

Waiting – the process is idle, waiting for 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 still occupies an entry in the process table.

7. How to use 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. What is the difference between cmp and diff ?

diff

shows the changes needed to make two files identical, presenting a line‑by‑line comparison. cmp performs a byte‑by‑byte comparison and reports the first mismatching byte.

9. Can the ls command be replaced by echo ?

Yes. echo * expands to the same list of filenames that ls would display, though formatting differs.

10. What is an inode?

An inode is a data structure used by Linux/Unix file systems to store metadata about a file, including a unique inode number that identifies the file on the disk.

These ten Q&A pairs cover essential Linux shell knowledge often asked in technical interviews.