Accessing variables ($var and ${var}) in Bash Scripting

Introduction

You use variables to store information and access their values easily in your script. Accessing variables with $var or ${var} lets you use the stored value wherever you need it.

When you want to print a stored value in your script.

When you need to combine a variable with other text or characters.

When you want to pass a variable's value as input to a command.

When you want to check or compare the value stored in a variable.

When you want to use variables inside strings or commands safely.

Syntax

Bash Scripting

echo $var
# or
echo ${var}

Use $var to access the value of a variable named var.

Use ${var} when you want to clearly separate the variable name from surrounding text.

Examples

Prints the value of the variable 'name'.

Bash Scripting

name="Alice"
echo $name

Uses ${name} to combine the variable with other text safely.

Bash Scripting

name="Alice"
echo Hello, ${name}!

Prints the value of 'count' inside a string.

Bash Scripting

count=5
echo "Count is $count"

Without braces, $var would be followed by 'ly' as part of the name. Braces separate the variable name.

Bash Scripting

var="world"
echo "Hello, ${var}ly!"

Sample Program

This script shows how to access variables with $var and ${var}. It also shows why braces are useful to separate variable names from text.

Bash Scripting

#!/bin/bash

user="Bob"

# Access variable without braces
 echo "Hello, $user"

# Access variable with braces and extra text
 echo "Hello, ${user}123"

# Show difference without braces
 echo "Hello, $user123"

# Assign a new variable
user123="Not Bob"

# Now print user123
 echo "Hello, ${user} and ${user123}"

Important Notes

Always use braces ${var} when you add letters or numbers right after the variable name to avoid confusion.

Variables are case sensitive in bash, so $User and $user are different.

You can use variables inside double quotes "" but not inside single quotes ''.

Summary

Use $var to access a variable's value simply.

Use ${var} to clearly separate the variable name from other text.

Braces help avoid mistakes when combining variables with other characters.