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Linux & Shell Scripting · Question Set
Shell Scripting Fundamentals interview questions for placements and exams.
Questions
14
Included in this set
Subject
Linux & Shell Scripting
Explore more sets
Difficulty
Mixed
Level of this set
Go through each question and its explanation. Use this set as a focused practice pack for Linux & Shell Scripting.
You can execute a script by running bash scriptname.sh, which starts a new shell. Alternatively, make it executable using chmod +x scriptname.sh and run it directly with ./scriptname.sh from the terminal.
chmod +x deploy.sh ./deploy.sh
Loops are widely used in DevOps for log monitoring, batch file renaming, or deployment verification. For instance, a for loop can iterate over multiple servers to check service availability automatically.
for host in server1 server2; do ping -c 1 $host done
In Bash, variables are declared without spaces around the equal sign. To use a variable later, prefix it with a dollar sign — for example, echo $var.
name=Vipul echo $name
The read command takes user input and stores it in a variable. You can use the -p flag to display a prompt before reading the input.
read -p 'Enter your name: ' username
In Bash, conditions are enclosed in square brackets with spaces around them. After then, you write the commands to execute if the condition is true, followed by fi to end the block.
if [ $age -gt 18 ]; then echo 'Adult' fi
Bash loops iterate over lists or sequences using the for-in-do-done structure. It can also use command substitution like for file in *.log; do echo $file; done.
for i in 1 2 3 4 5; do echo $i done
A while loop keeps executing as long as the test condition is true. It is commonly used for reading files line by line or running background checks.
while [ $count -le 5 ]; do echo $count ((count++)) done
The case statement in Bash ends with the keyword 'esac', which is 'case' spelled backward. It’s used for multi-branch conditions similar to switch-case in other programming languages.
case $option in 1) echo 'Start';; 2) echo 'Stop';; *) echo 'Invalid';; esac
The special variable $? holds the exit status of the most recent command. A value of 0 means success, while any non-zero value indicates an error or failure.
cp file.txt /backup/ echo $?
Functions in shell scripts are defined using the function keyword or simply the function name followed by parentheses. They help group reusable code blocks and make scripts modular.
function greet() {
echo 'Hello User'
}
greetArithmetic can be done using double parentheses (( )), expr, or the let command. For example, result=$((a + b)) is preferred because it’s concise and supports multiple operators without needing escape characters.
a=5; b=10; sum=$((a + b)); echo $sum
You can use the -z flag to test if a string is empty and -n to test if it’s not. Conditional checks like if [ -z "$name" ]; then echo 'Empty'; fi help control program flow based on user input.
if [ -z "$input" ]; then echo 'Empty' fi
If-else statements help control execution flow based on conditions. For example, checking if a service is running before restarting it. This prevents unnecessary downtime or duplicate operations in automation scripts.
if systemctl is-active --quiet nginx; then echo 'Nginx is running' else systemctl start nginx fi
The line '#!/bin/bash' is known as a shebang. It instructs the operating system to use the Bash shell to interpret the script. Without it, the system may use a different default shell, which could cause compatibility issues.
#!/bin/bash
For complete preparation, combine this set with full subject-wise practice for Linux & Shell Scripting. You can also explore other subjects and sets from the links below.