Bash Scripting Interview Questions for DevOps (2026)

Every DevOps engineer needs to write Bash. How do you make your scripts robust and error-proof?

1. What does set -euxo pipefail do?

This is the unofficial Bash strict mode.

• \-e\: Exit immediately if a command exits with a non-zero status.
• \-u\: Treat unset variables as an error.
• \-x\: Print commands as they are executed.
• \-o pipefail\: The pipeline fails if any command in it fails.

2. How do you find and delete files older than 30 days?

\find /path -type f -mtime +30 -exec rm {} \\;\

Or more efficiently: \find /path -type f -mtime +30 | xargs rm\

3. What is the difference between $# and $@?

\$#\ gives the number of arguments passed to the script.

\$@\ gives all the arguments passed to the script as separate words.

4. How do you read a file line by line?

\\\`bash

while IFS= read -r line; do

echo "$line"

done < input.txt

\\\`

5. What are exit codes in Bash?

Exit codes indicate the success or failure of a command. \0\ means success, any non-zero value (1-255) means failure. The exit code of the last run command is stored in \$?\.

6. How do you replace a string in a file?

Using \sed\: \sed -i 's/old_string/new_string/g' filename\

7. What is process substitution?

Process substitution \<(cmd)\ or \>(cmd)\ allows the output (or input) of a command to appear as a temporary file. Useful for commands that expect files, e.g., \diff <(ls dir1) <(ls dir2)\.

8. What does 2>&1 mean?

It redirects standard error (file descriptor 2) to standard output (file descriptor 1). This combines both stdout and stderr streams.

9. How do you extract the second column of a CSV file?

Using \awk\: \awk -F',' '{print $2}' file.csv\

Or using \cut\: \cut -d',' -f2 file.csv\

10. How do you check if a variable is empty?

\\\`bash

if [ -z "$VAR" ]; then

echo "Variable is empty"

fi

\\\`

11. What is the difference between single and double quotes?

Single quotes (\'\) are literal; variables and commands inside them are NOT evaluated. Double quotes (\"\) allow variable expansion and command substitution (\$VAR\ and \$(cmd)\ are evaluated).

12. How do you run a script in the background?

Append an ampersand \&\ to the command: \./script.sh &\. To keep it running after logging out, use \nohup ./script.sh &\.

13. How do you get the directory of the currently running script?

\DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"\

14. Explain what awk does.

\awk\ is a versatile text processing tool that operates on records (lines) and fields (columns). It is widely used for data extraction, reporting, and manipulating structured text.

15. How do you test if a directory exists?

\\\`bash

if [ -d "/path/to/dir" ]; then

echo "Exists"

fi

\\\`

16. What is the shebang (#!)?

It is the first line of a script (\#!/bin/bash\) indicating which interpreter the OS should use to execute the file.

17. How do you define a function in Bash?

\\\`bash

my_function() {

echo "Argument 1 is $1"

}

my_function "Hello"

\\\`

18. How do you handle default variable values?

Using parameter expansion: \MY_VAR=${MY_VAR:-default_value}\ assigns "default_value" if MY_VAR is unset or empty.

19. How do you parse command line arguments using getopts?

\\\`bash

while getopts "a:b:" opt; do

case $opt in

a) arg_a="$OPTARG" ;;

b) arg_b="$OPTARG" ;;

esac

done

\\\`

20. How do you use cron to schedule a script?

Edit the crontab with \crontab -e\ and add a line like \0 5 * * * /path/to/script.sh\ to run the script every day at 5:00 AM.