Top 10 Linux Shell Interview Questions and How to Solve Them

1. How to interrupt a shell script before it finishes? 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 error at the exit -1 line.

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 in‑place option simplifies it: sed -i '1 d' file.txt.

3. How to check the length of a specific line in a text file? Combine sed with wc, e.g., sed -n '5 p' linuxmi.txt | wc -c to get the character count of line 5.

4. How to view all non‑printing characters in a file? Open the file in vi, enter command mode with :, and run set list. This displays characters such as ^M.

5. Create a shared directory where members can create or access files but cannot delete others' files. Use the sticky bit:

# 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 columns or character ranges, e.g., cut -c1-10 txt_linuxmi for the first ten characters, or cut -d';' -f2 -f5 -f7 txt_linuxmi for specific fields. 8. Difference between cmp and diff ? cmp compares files byte‑by‑byte and reports the first mismatch, while 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/Unix to store metadata about a file; each file has a unique inode number.