Shell Scripting Interview Questions

Beginner-Level Shell Scripting Interview Questions

1. What's a shell in Unix/ Linux?

In the Linux or Unix world, a shell is a command-line interpreter that acts as the ground between the user and the system's core( the kernel). It takes users’ commands, interprets them, and executes them. You can suppose of it as a user-friendly interface to run programs, manage lines, or indeed automate tasks via scripts.

So, if you are also looking forward to starting your journey in the sphere of Linux or the Unix world,  you can refer to our blog on Linux Interview Questions and Answers, and along with that, enroll in our CompTIA Linux+ Certification Training.

 2. Can you describe the different stages in a Linux process life cycle?

A Linux process generally goes through these four stages

Waiting – The process is paused and is currently waiting for a required resource to become available.
Running – The process is actively executing on the CPU.
Stopped – The process has been halted, basically after completing its execution successfully.
Zombie – The process has completed execution, but its entry remains in the process table because its parent has not yet acknowledged its termination.

This is foundational knowledge for numerous Linux scripting interview questions.

3. What's a superblock, and does it relate to shell scripting?

The superblock isn’t directly used in shell scripting, but it’s truly important in the Linux filesystem. It holds metadata about the filesystem, such as its size and inode word. It's more applicable in Linux administration, but understanding it helps when writing Unix shell scripts that interact with storage.

4. What are the common shell types used in Linux systems?

Linux supports several types of shells. The most extensively used ones include

Bash( Bourne Again SHell) – Most common.
Sh( Bourne Shell) – The original shell.
Ksh( Korn Shell) – Combines features of C and Bourne shell.
Tcsh – Enhanced interpretation of C Shell.
Zsh( Z Shell) – largely customizable.

These frequently come up in interview questions for shell scripting.

 5. How would you define a shell variable?

A shell variable is a vessel to store data (like strings or figures) in a shell session or script. For illustration

name = " Alice"

echo$ name

Variables are extremely important when writing dynamic and applicable Unix shell scripts.

6. What are the ways to connect to a database garçon from a shell script?

You can use tools such as 

mysql for MySQL/ MariaDB

psql for PostgreSQL

SQLPlus for Oracle

illustration

mysql- u username- p- h host_name- e" elect * FROM db.table;"

This kind of question constantly appears in shell scripting questions for an interview when integrating scripts with backend databases.

7. What’s the part of the shebang(#!) line in a shell script?

The shebang line (like #!/caddy/bash) at the top of a script tells the system which interpreter should run the script. Without it, the OS may not know how to execute the file.

8. Is there a command you can use instead of echo?

Yes! You can use the printf command as an alternative

printf “Hello, World\n”

It’s more flexible, especially for formatting.

9. What are metacharacters in shell scripting?

Metacharacters are special symbols that the shell interprets in a specific way. exemplifications include

*( wildcard)

I ( pipe)

( redirect output)

&( run in background)

Learning metacharacters is truly essential when it comes to handling shell scripting interview questions.

10. How would you explain an interpreter?

An interpreter reads and executes code line by line. Shell scripts mostly rely on interpreters such as Bash, which process each command sequentially.

11. What about a compiler?

A compiler translates the entire source code into machine code before execution. Unlike an interpreter, it doesn’t execute line by line — it compiles everything first.

12. Why would someone choose CLI over GUI?

The Command Line Interface( CLI) is truly lightweight, fast, and scriptable. 

It allows precise control and is essential for automation using shell scripting. While GUIs are user-friendly, CLIs are truly necessary for developers and sysadmins.

13. What exactly is shell scripting?

Shell scripting is the practice of writing sequences of commands in a file to automate tasks. It’s extensively used in system administration, task scheduling, and process automation.

14. Why is shell scripting important in Linux environments?

Shell scripting saves time by automating certain repetitive tasks. It also enriches system effectiveness along with consistency. 

In most interview questions for Unix shell scripting, understanding the various benefits of automation is truly critical.

15. What’s the default shell for user login, and how do you change it?

The default login shell is generally Bash. To change it

chsh- s/ caddy/ zsh

You’ll need to log out and back in for changes to apply.

16. How can you check if a link is hard or soft( symbolic )?

Use the ls- l command

A soft link shows in the morning and points to another path.

A hard link looks like a normal file but shares the same inode as the original.

Also, ls -is displays inodes — identical inodes indicate a hard link.

17. Why do we use shell scripts in Unix/ Linux systems?

We use shell scripts to automate routine tasks, similar to: 

Backups

Log rotation

Batch file processing

System monitoring

Similar use cases frequently come up in Unix script interview questions.

18. What are the various types of shells available in Unix/ Linux?

Here, we have provided a list of all the different types of shells that are available in Unix/Linux

Bash – Most extensively used.
Ksh – Useful for scripting and interactive use.
Csh – C- suchlike syntax.
Tcsh – An enriched interpretation of Csh.
Zsh – largely customizable.
Dash—A Lightweight shell used in some Linux distros.

Thus, we can say that knowing the differences helps in Shell scripting interview questions. 

19. What does the term" shell variable" relate to?

A shell variable stores data used by the shell and scripts. These can be environment variables($ HOME,$ PATH) or user-defined ones. One more important thing that we must remember is, they are very helpful when it comes to controlling the behaviour of the shell and scripts.

20. Can you explain positional parameters in shell scripting?

Positional parameters are special variables($ 1,$ 2,$ 3, etc.) that hold command-line arguments passed to a script.

An example of this can be

 !/ caddy/ bash

echo" First arg$1"

echo" Alternate arg$2"

This is also one of the most asked Unix shell scripting interview questions. 

Still, especially around shell scripting questions for interviews or broader Linux scripting interview questions, this guide will definitely give you a solid foundation if you are looking forward to advancing in your career. 

Intermediate-level Shell Scripting Interview Questions

21. What's GUI scripting, and how is it different from traditional shell scripting?

GUI scripting involves automating interactions with graphical user interfaces( windows, buttons, controls) rather than command-line interfaces. For example, rather than codifying a command, GUI scripts can simulate mouse clicks or keyboard input.

Even though shell scripting focuses on CLI-based automation in Unix/ Linux, GUI scripting is generally used in environments like Windows with tools such as AutoIt or Sikuli.

This content may pop up in shell scripting interview questions that explore cross-platform automation skills.

22. How long does a shell variable live?

The lifetime of a shell variable depends on where it’s declared

Local variables live only during the execution of the shell or script.

Exported variables (environment variables) can be passed to child processes, but disappear once the session ends.

Thus, we can see that understanding this is no doubt very critical in numerous interview questions for shell scripting, especially when discussing scope and environment inheritance.

23. Is it possible to pass parameters to a script while it’s executing in Unix?

Yes, you can pass arguments to a Unix shell script using command-line parameters

/ myscript.sh arg1 arg2

Inside the script, use$ 1,$ 2, etc., to access them. This is frequently tested in Unix script interview questions to check knowledge of dynamic script running.

24. What are the common downsides of using shell scripts?

While shell scripting is important, it does come with some downsides: 

I. Not ideal for large operations

II. Difficult debugging (especially for complex scripts)

III. Security pitfalls( scripts can be altered if not duly secured)

IV. Shell-specific syntax( scripts may not be movable across shells)

This again is one of the important shell scripting questions for interview sessions to assess the mindfulness of limitations.

25. Can you explain the difference between absolute and relative paths in Linux?

Absolute path - Full path from the root directory.

Example:  / home/ user/ docs / file.txt

Relative path -  Path from your current working directory.

illustration./ croakers / file.txt

These are must-know shell scripting interview questions, especially when handling file and directory operations.

26. What do the head and tail commands do in shell scripting?

head - Displays the first 10 lines of a file( default behaviour ).
Example:  head filename.txt
Tail -  Shows the last 10 lines by default.
Example - tail filename.txt

These are fundamental commands frequently covered in shell scripting interview questions related to log file analysis or monitoring.

27. How do you create shortcuts (symbolic links) in Linux?

Use the ln command

ln- s/ path/ to/ original/ path/ to/ roadway

This creates a symbolic ( soft) link. It’s an essential concept in numerous shell scripting interview questions, especially when managing scripts or configuration lines.

28. Which files are associated with the crontab command?

Two primary lines associated with crontab are

/etc/ crontab – System-wide cron file..

crontab or crontab- e –user-specific cron jobs.

This is generally asked in interview questions for Unix shell scripting, especially under automation and scheduling topics.

29. What command is used to compare strings in shell scripts?

Use the test command or() classes

if("$ str1" = "$ str2"); also

echo" Strings are equal"

fi

You might also use [[ ]] for extended comparison. This is standard in shell programming interview questions that cover conditionals.

30. What’s the correct syntax for different circles in shell scripting?

In shell scripting, there are three main types of loops used to execute a block of code repeatedly: for, while, and until loops. Here's the correct syntax and explanation for each:

I. For Loop

The for loop iterates over a list of items.

Syntax:

for i in 1 2 3; do

  echo $i

done

Explanation:

- > This loop will iterate over the values 1, 2, and 3, printing each one.

II. While Loop

The while loop continues to execute as long as the condition is true.

Correct Syntax:

count=0

while [ $count -lt 5 ]; do

  echo $count

  count=$((count + 1))

done

Explanation:

- > The loop starts with count = 0 and runs while count is less than 5.
- > In each iteration, it prints the current value and increments it.

III. Until Loop

The until loop is the opposite of while: it continues to execute as long as the condition is false.

Correct Syntax:

count=0

until [ $count -ge 5 ]; do

  echo $count

  count=$((count + 1))

done

Explanation:

-> This loop runs until count becomes greater than or equal to 5.
-> It works similarly to the while loop but with a reversed condition.

These loop constructs are foundational in shell scripting and are widely used in automation scripts, system monitoring, and task scheduling, skills that are especially valuable for roles like DevOps Engineers.

Advanced-Level Shell Scripting Interview Questions

31. How can you extract a portion of a string using echo in bash?

You can use parameter expansion along with the echo command if you ever need to publish just part of a string variable in bash.

For example

mystring = " ShellScriptingIsPowerful"

echo${ mystring59}

Explanation

5 is the starting indicator( 0- based)

9 is the number of characters to prize

Output: Scripting

This is a classic in shell scripting interview questions as it demonstrates your capability to manipulate strings without relying on external tools like cut or awk.

32. How do you display a substring in a bash shell script?

In bash, there’s a neat and effective way to get substrings using built-in features, where there’s no external command demanded.

Syntax

{ variablepositionlength}

For example

textbook = " linuxscriptinginterview"

echo${ text05}

Output:  linux

This is one of the most common shell scripting questions for interviews and constantly shows up in both Linux scripting interview questions and Unix script interview questions.

33. What approach do you take to troubleshoot a shell script when debugging isn’t working?

When you are debugging a shell script, there are some practical and extensively used ways : 

Turn on debugging mode

!/ caddy/ bash- x

Or within the script

set- x# launch debugging

Your script sense

set x# Stop debugging

Use echo or printf statements

To trace the values of variables or progress through the script.

Exit on error

set- e

Extra Tip:  You can also use a tape to catch errors or signals and log them.

These strategies are essential in interview questions for shell scripting, where you’re tested on problem-solving within scripts.

34. What does the difference between(($ string == " efg *")) and(($ string == efg *)) actually mean in bash?

This is a tricky but important distinction and one that frequently pops up in shell programming interview questions.

Let’s break it down

Case 1(($ string == " efg *"))

The pattern is inside quotations, so it's treated literally.

Meaning :  it'll only match a string that's exactly efg *, with the asterisk included.

Case 2(($ string == efg *))

No quotations around efg *, so bash treats the * as a wildcard.

Meaning :  it matches any string that starts with efg, like efg123, efgHello, etc.

Again, one of the very important shell scripting interview questions, this difference tests your understanding of pattern matching vs string literals — a subtle yet pivotal part of writing dependable bash scripts.

35. Why is Bash considered a weakly typed language?

Bash is considered a weakly typed language because it doesn’t require you to declare data types when creating variables; rather, it treats all variables as strings by default, and the type is interpreted based on the value at runtime. 

An example can be, you assign a number to a variable and then change it to a string without any errors. Even though Bash does offer the declare command to assign attributes like integer(- i) or read-only (- r), its type enforcement is minimal and voluntary, and also, Bash lacks native support for certain data types like floating-point figures, taking external tools like bc or awk for similar operations. This inflexibility is useful but can lead to subtle bugs, especially in computation or data-sensitive scripts. 

Thus, we can agree that understanding this behaviour is essential for handling shell scripting interview questions, particularly those that assess knowledge of variable running in Unix and Linux scripting environments.

Conclusion

A solid understanding of scripting concepts, real-world practical experience, and problem-solving skills are very necessary when you prepare for the interview questions for shell scripting. 

Focus on fundamental ideas like loops, variables, file handling, and process management. If you want to ace these kinds of interviews, you need to improve your logic, regularly write and debug programs, and investigate real-world situations. Examining typical shell scripting interview questions might help you spot trends and boost your self-assurance.

Additionally, it's critical to properly describe your reasoning process during interviews. To enhance your abilities, make use of resources such as forums, online tutorials, and practice interviews. Being ready for shell scripting interview questions improves your technical proficiency and your capacity to manage difficult issues under duress.