The simple case

Frequently, string comparison is done using the test operator, [. This is ill-advised in bash, as there's a much more convenient format for string comparison, using the case statement. Here's a simple example:

 testcase() {
 for VAR; do
 case “${VAR}” in
         '') echo “empty”;;
         a) echo “a”;;
        b) echo “b”;;
        c) echo “c”;;
        *) echo “not a, b, c”;;
 esac
 done
 }
 testcase '' foo a bar b c d

The testcase function lets us test the case statement by wrapping it in a for loop that assigns each function argument to the VAR variable, then executes the case statement. With the foo a bar b c d arguments, we can expect the following output:

 empty
 not a, b, c
 a
 not a, b, c
 b
 c
 d