How to write multiple line strings using Bash with variables on Linux?

Bash supports multiple approaches for creating and handling multiline strings. This functionality is essential when working with formatted output, configuration files, or complex text processing tasks in shell scripts.

There are three primary methods to create multiline strings in Bash, each with its own advantages depending on the use case.

Method 1: Using
Escape Sequences

The simplest approach uses the
newline character to separate lines within a string. This method works well for short strings and when you need precise control over formatting.

Example

#!/bin/bash
approach1="First Line Text\nSecond Line Text\nThird Line Text"
echo -e "$approach1"

First Line Text
Second Line Text
Third Line Text

Note: The -e flag with echo enables interpretation of backslash escapes like
.

Method 2: Literal Multiline Strings

You can define multiline strings by literally breaking lines within double quotes. This approach is more readable for longer text blocks and preserves the exact formatting as written.

Example

#!/bin/bash
approach2="First Line Text
Second Line Text
Third Line Text"
echo "$approach2"

First Line Text
Second Line Text
Third Line Text

Important: Always enclose the variable in double quotes when echoing to preserve the newlines.

Method 3: Using Heredoc (Here Documents)

The Heredoc approach is most powerful for complex multiline strings, especially when dealing with formatted text, code blocks, or configuration files. It allows you to include special characters and maintains exact formatting.

Example

#!/bin/bash
read -r -d '' MULTI_LINE_VAR_STRING << EOM
First Line Text
Second Line Text
Third Line Text
EOM

echo "$MULTI_LINE_VAR_STRING"

First Line Text
Second Line Text
Third Line Text

Comparison of Methods

Working with Variables in Multiline Strings

All three methods support variable interpolation when using double quotes:

#!/bin/bash
name="John"
age=25

# Method 1 with variables
message1="Hello $name\nYou are $age years old"
echo -e "$message1"

# Method 2 with variables  
message2="Hello $name
You are $age years old"
echo "$message2"

Conclusion

Bash provides flexible options for creating multiline strings, from simple
escapes to powerful Heredoc syntax. Choose the method that best fits your specific needs: escape sequences for simple cases, literal multiline for readability, and Heredoc for complex formatted text with variables.