Top 10 Linux Shell Interview Questions and Practical Answers

Linux offers a vast landscape for learning useful shell commands that can boost both career and knowledge.

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

Use the exit command. Providing a non‑zero status, such as exit -1, forces the script to terminate with an error.

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

Running the script shows the exit command stops execution before the final echo.

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

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

The sed command can delete the first line:

# sed '1 d' file.txt

Using the -i option edits the file in place:

# sed -i '1 d' file.txt

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

Combine sed with wc:

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

An example command to get the length of line 5:

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

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

Open vi, press Esc, then type :set list. This displays characters such as ^M.

Note: This method shows all non‑printable characters, including Ctrl+M (^M).

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

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

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

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

Waiting : the process is waiting for resources.

Running : the process is actively executing.

Stopped : the process has finished or received a kill signal.

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

7. How to use the cut command?

Extract the first 10 columns of a file:

# cut -c1-10 txt_linuxmi

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

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

8. 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.

9. Can echo replace ls ?

Yes. echo * lists directory contents similarly to ls.

10. What is an inode?

An inode is a data structure used by Linux to uniquely identify a file; each file has its own inode number.