How to concatenate string variables in Bash

Question

In PHP, strings are concatenated together as follows:

$foo = \"Hello\";
$foo .= \" World\";

Here, $foo becomes \"Hello World\"

Answer 1

I prefer to use curly brackets ${} for expanding variable in string:

foo="Hello"
foo="${foo} World"
echo $foo
> Hello World

---

Curly brackets will fit to Continuous string usage:

foo="Hello"
foo="${foo}World"
echo $foo
> HelloWorld

Otherwise using foo = "$fooWorld" will not work.