How to concatenate string variables in Bash

Overview

We can concatenate string variables by using bash in the following two ways: 

  1. Writing them one after the other
  2. Using the += operator

Syntax

#first way

var_name = "${string variable name} provide string here"



#second way

variabe_name+="provide string here"
  • The first way is useful when we want to concatenate the string and store it in a different variable.
  • The second way is useful when we want to concatenate the string and store it in the same variable.

Example

# given string
str1="Hello"
#concatenate using first way
str2="${str1} World"
echo $str2
#concatenate using second way
str1+=" World"
echo $str1

Explanation

  • Line 2: We declare and initialize the first string variable, str1.
  • Line 5: We declare the second string variable, str2, and initialize it by concatenating the first way.
  • Line 9: We concatenate the string to the same variable using the += operator and store it in the same variable.

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