Bash if...else Statement

When writing shell scripts, you will often need to run different commands depending on whether a condition is true or false. Bash provides the if, if...else, and if...elif...else statements to handle exactly that, letting you branch your script logic based on test results, exit codes, or file checks.

This guide walks through each form of the Bash if statement with practical examples.

if Statement #

Bash if conditionals can have different forms. The most basic if statement takes the following form:

if TEST-COMMAND
then
  STATEMENTS
fi

The if statement starts with the if keyword followed by the conditional expression and the then keyword. The statement ends with the fi keyword.

If the TEST-COMMAND evaluates to True, the STATEMENTS are executed. If the TEST-COMMAND returns False, nothing happens; the STATEMENTS are ignored.

As a general practice, indent your code and separate code blocks with blank lines. Most people use either 4-space or 2-space indentation. Indentations and blank lines make your code more readable and organized.

The following example script checks whether a given number is greater than 10:

#!/bin/bash

echo -n "Enter a number: "
read VAR

if [[ $VAR -gt 10 ]]
then
  echo "The variable is greater than 10."
fi

Save the code in a file and run it from the command line:

bash test.sh

The script will prompt you to enter a number. If, for example, you enter 15, the test command will be evaluated as true because 15 is greater than 10, and the echo command inside the then clause will be executed.

The variable is greater than 10.

if...else Statement #

The Bash if...else statement takes the following form:

if TEST-COMMAND
then
  STATEMENTS1
else
  STATEMENTS2
fi

If the TEST-COMMAND evaluates to True, the STATEMENTS1 will be executed. Otherwise, if TEST-COMMAND returns False, the STATEMENTS2 will be executed. You can have only one else clause in the statement.

Adding an else clause to the previous script gives a message for both outcomes:

#!/bin/bash

echo -n "Enter a number: "
read VAR

if [[ $VAR -gt 10 ]]
then
  echo "The variable is greater than 10."
else
  echo "The variable is less than or equal to 10."
fi

If you run the code and enter a number, the script will print a different message based on whether the number is greater or less/equal to 10.

if...elif...else Statement #

The Bash if...elif...else statement takes the following form:

if TEST-COMMAND1
then
  STATEMENTS1
elif TEST-COMMAND2
then
  STATEMENTS2
else
  STATEMENTS3
fi

If the TEST-COMMAND1 evaluates to True, the STATEMENTS1 will be executed. If the TEST-COMMAND2 evaluates to True, the STATEMENTS2 will be executed. If none of the test commands evaluate to True, the STATEMENTS3 will be executed.

You can have one or more elif clauses in the statement. The else clause is optional.

The conditions are evaluated sequentially. Once a condition returns True, the remaining conditions are not tested, and program control moves to the end of the if statements.

Adding an elif clause handles the equal case as well:

#!/bin/bash

echo -n "Enter a number: "
read VAR

if [[ $VAR -gt 10 ]]
then
  echo "The variable is greater than 10."
elif [[ $VAR -eq 10 ]]
then
  echo "The variable is equal to 10."
else
  echo "The variable is less than 10."
fi

Nested if Statements #

Bash allows you to nest if statements within if statements.

You can place multiple if statements inside another if statement.

The following script will prompt you to enter three numbers and print the largest number among the three numbers.

#!/bin/bash

echo -n "Enter the first number: "
read VAR1
echo -n "Enter the second number: "
read VAR2
echo -n "Enter the third number: "
read VAR3

if [[ $VAR1 -ge $VAR2 ]]
then
  if [[ $VAR1 -ge $VAR3 ]]
  then
    echo "$VAR1 is the largest number."
  else
    echo "$VAR3 is the largest number."
  fi
else
  if [[ $VAR2 -ge $VAR3 ]]
  then
    echo "$VAR2 is the largest number."
  else
    echo "$VAR3 is the largest number."
  fi
fi

Here is what the output will look like:

Enter the first number: 4
Enter the second number: 7
Enter the third number: 2
7 is the largest number.

Multiple Conditions #

The logical OR and AND operators allow you to use multiple conditions in the if statements.

Here is another version of the script to print the largest number among the three numbers. In this version, instead of the nested if statements, we are using the logical AND (&&) operator.

#!/bin/bash

echo -n "Enter the first number: "
read VAR1
echo -n "Enter the second number: "
read VAR2
echo -n "Enter the third number: "
read VAR3

if [[ $VAR1 -ge $VAR2 ]] && [[ $VAR1 -ge $VAR3 ]]
then
  echo "$VAR1 is the largest number."
elif [[ $VAR2 -ge $VAR1 ]] && [[ $VAR2 -ge $VAR3 ]]
then
  echo "$VAR2 is the largest number."
else
  echo "$VAR3 is the largest number."
fi

Test Operators #

In Bash, the test command takes one of the following syntax forms. For a complete guide on numeric comparisons, see our Bash comparison operators tutorial.

test EXPRESSION
[ EXPRESSION ]
[[ EXPRESSION ]]

To make the script portable, prefer using the old test [ command, which is available on all POSIX shells. The newer version of the test command [[ (double brackets) is supported on most modern systems using Bash, Zsh, and Ksh as default shells.

To negate the test expression, use the logical NOT (!) operator. When comparing strings , always use single or double quotes to avoid word splitting and globbing issues.

Below are some of the most commonly used operators:

• -n VAR - True if the length of VAR is greater than zero.
• -z VAR - True if the VAR is empty.
• STRING1 = STRING2 - True if STRING1 and STRING2 are equal.
• STRING1 != STRING2 - True if STRING1 and STRING2 are not equal.
• INTEGER1 -eq INTEGER2 - True if INTEGER1 and INTEGER2 are equal.
• INTEGER1 -gt INTEGER2 - True if INTEGER1 is greater than INTEGER2.
• INTEGER1 -lt INTEGER2 - True if INTEGER1 is less than INTEGER2.
• INTEGER1 -ge INTEGER2 - True if INTEGER1 is equal or greater than INTEGER2.
• INTEGER1 -le INTEGER2 - True if INTEGER1 is equal or less than INTEGER2.
• -h FILE - True if the FILE exists and is a symbolic link.
• -r FILE - True if the FILE exists and is readable.
• -w FILE - True if the FILE exists and is writable.
• -x FILE - True if the FILE exists and is executable.
• -d FILE - True if the FILE exists and is a directory.
• -e FILE - True if the FILE exists and is a file, regardless of type (node, directory, socket, etc.).
• -f FILE - True if the FILE exists and is a regular file (not a directory or device).

Here are a few practical examples using common operators.

Check whether two strings are equal:

#!/bin/bash

read -p "Enter your username: " USER

if [[ "$USER" = "admin" ]]
then
  echo "Welcome, admin."
else
  echo "Access denied."
fi

Check whether a variable is empty:

#!/bin/bash

read -p "Enter a value: " INPUT

if [[ -z "$INPUT" ]]
then
  echo "No value provided."
fi

Check whether a file exists before reading it:

#!/bin/bash

FILE="/etc/hosts"

if [[ -f "$FILE" ]]
then
  echo "$FILE exists."
else
  echo "$FILE not found."
fi

One-Line Syntax #

You can write if statements on a single line, which is useful for simple conditions:

if [[ $VAR -gt 10 ]]; then echo "Greater than 10"; fi

With if...else:

if [[ $VAR -gt 10 ]]; then echo "Greater"; else echo "Smaller or equal"; fi

Short-Circuit Evaluation #

For simple conditions, you can use the logical AND (&&) and OR (||) operators as a shorthand:

[[ $VAR -gt 10 ]] && echo "Greater than 10"

This is equivalent to:

if [[ $VAR -gt 10 ]]; then
  echo "Greater than 10"
fi

You can also combine both operators for an if...else effect:

[[ $VAR -gt 10 ]] && echo "Greater" || echo "Smaller or equal"

Quick Reference #

Conclusion #

For a full list of test expressions you can use in your conditions, see our Bash comparison operators guide. If you need to match a single variable against many values, the Bash case statement is worth a look.

About the authors

Dejan Panovski

Dejan Panovski is the founder of Linuxize, an RHCSA-certified Linux system administrator and DevOps engineer based in Skopje, Macedonia. Author of 800+ Linux tutorials with 20+ years of experience turning complex Linux tasks into clear, reliable guides.

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