How to Declare Variables in Bash: Simple Syntax and Examples

In Bash, you declare a variable by writing its name followed by an equals sign and the value without spaces, like name=value. You can then use the variable by prefixing it with a dollar sign, for example, $name.

Syntax

To declare a variable in Bash, use the format variable_name=value without spaces around the equals sign. Variable names can include letters, numbers, and underscores but cannot start with a number. To access the value, prefix the variable name with a dollar sign $.

bash

variable_name=value

# Example:
name=John

# Accessing the variable:
echo $name

Example

This example shows how to declare a variable and print its value using echo. It demonstrates storing a string and then displaying it.

bash

# Declare a variable
name=Alice

# Print the variable's value
echo "Hello, $name!"

Output

Hello, Alice!

Common Pitfalls

Common mistakes include putting spaces around the equals sign, which causes errors, or forgetting to use $ when accessing the variable. Also, variables are case-sensitive, so name and Name are different.

bash

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

# Right: no spaces
name=John

# Wrong: missing $ when accessing
# echo name

# Right: use $ to access
name=John
echo $name

Output

John

Quick Reference

Action	Syntax	Notes
Declare variable	variable_name=value	No spaces around =
Access variable	$variable_name	Use $ to get value
Assign string with spaces	variable_name="value with spaces"	Use quotes for spaces
Unset variable	unset variable_name	Removes the variable

Key Takeaways

Declare variables without spaces around the equals sign.

Use $ before the variable name to access its value.

Variable names are case-sensitive and cannot start with numbers.

Use quotes when assigning values with spaces.

Avoid common errors like spaces around = or missing $ when accessing.