Learning Linux Shell Scripting - Second Edition

Using the test command with double brackets

Let's consider a case where we want to check whether there is the name Ganesh and whether his friend is John. In this case, we will have multiple expressions to be checked using the AND operator, &&. In such a case, we can use the following syntax:

    $ [[ $name == Ganesh && $friend == "John" ]]
  

Another way to do this is as follows:

    [ $name == Ganesh ] && [ $friend == "John" ]
  

We used double brackets in the preceding expressions.

Here, we want to evaluate multiple expressions on the same command line. We can use the preceding syntax with AND (&&) or OR (||) logical operators.