How to use variable in bash

Bash-scriptingHow-ToBeginner · 3 min read

How to Use Variables in Bash: Syntax and Examples

In Bash, you create a variable by writing its name followed by an equal sign and the value without spaces, like name=value. To use the variable's value, prefix its name with a dollar sign, for example, $name.

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Syntax

To create a variable in Bash, write the variable name, then an equal sign =, and then the value with no spaces around the equal sign. To use the variable, prefix its name with $.

Variable assignment: variable_name=value
Variable usage: $variable_name

bash

variable_name=value

# Use the variable
 echo $variable_name

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Example

This example shows how to assign a value to a variable and then print it using echo. It demonstrates the basic use of variables in Bash scripts.

bash

#!/bin/bash

name=Alice

echo "Hello, $name!"

Output

Hello, Alice!

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Common Pitfalls

Common mistakes include putting spaces around the equal sign during assignment, which causes errors, and forgetting to use $ when accessing the variable's value.

Also, quoting matters: use quotes around variables when the value contains spaces to avoid word splitting.

bash

# Wrong: spaces around = cause error
# name = Alice

# Correct:
name=Alice

# Wrong: missing $ when using variable
# echo name

# Correct:
echo $name

# Handling spaces in values
full_name="Alice Smith"
echo "$full_name"

Output

Alice Alice Smith

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Quick Reference

Action	Syntax	Example
Assign a variable	variable=value	name=Bob
Use a variable	$variable	echo $name
Assign with spaces	variable="value with spaces"	full_name="Bob Smith"
Use variable in string	"Hello, $variable!"	echo "Hello, $name!"

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Key Takeaways

Assign variables without spaces around the equal sign, like name=Alice.

Use $ before the variable name to access its value, for example, $name.

Quote variables when their values contain spaces to preserve them.

Avoid common mistakes like spaces in assignment or missing $ when using variables.