How to Use If Else in Bash: Simple Syntax and Examples

In bash, use if followed by a condition and then to run commands if true. Use else to run commands if the condition is false, ending with fi to close the block.

Syntax

The basic if else structure in bash looks like this:

• if: starts the condition check
• condition: a command or test that returns true or false
• then: begins the commands to run if condition is true
• else: begins the commands to run if condition is false
• fi: ends the if block

bash

if [ condition ]; then
  # commands if true
else
  # commands if false
fi

Example

This example checks if a number is greater than 10 and prints a message accordingly.

bash

#!/bin/bash
number=15
if [ "$number" -gt 10 ]; then
  echo "Number is greater than 10"
else
  echo "Number is 10 or less"
fi

Output

Number is greater than 10

Common Pitfalls

Common mistakes include missing spaces around brackets, forgetting fi, or using incorrect test operators.

Wrong example (missing spaces):

if ["$number"-gt10]; then echo "Yes"; fi

Correct example:

bash

if [ "$number" -gt 10 ]; then
  echo "Yes"
fi

Quick Reference

Keyword	Purpose
if	Start condition check
[ condition ]	Test condition with spaces around brackets
then	Commands if condition is true
else	Commands if condition is false
elif	Else if for multiple conditions
fi	End if block

Key Takeaways

Always put spaces around brackets in conditions: [ condition ].

Close every if block with fi to avoid syntax errors.

Use -gt, -lt, -eq for numeric comparisons inside [ ].

Use else to run commands when the if condition is false.

Test your script with simple examples to catch syntax mistakes early.