Introduction
By default, every variable in bash is global to every function, script and even the outside shell if you are declaring your variables inside a script.
If you want your variable to be local to a function, you can use local to have that variable a new variable that is independent to the global scope and whose value will only be accessible inside that function.
Global variables
var="hello"
function foo(){
echo $var
}
foo
Will obviously output "hello", but this works the other way around too:
function foo() {
var="hello"
}
foo
echo $var
Will also output "hello"
Local variables
function foo() {
local var
var="hello"
}
foo
echo $var
Will output nothing, as var is a variable local to the function foo, and its value is not visible from outside of it.
Mixing the two together
var="hello"
function foo(){
local var="sup?"
echo "inside function, var=$var"
}
foo
echo "outside function, var=$var"
Will output
inside function, var=sup?
outside function, var=hello
