Learning Linux Shell Scripting

Understanding the test command

Let's now understand the test command.

Using the test command with single brackets

Let's learn the following example to check the content or value of expressions:

$ test $name = Ganesh
$ echo $?
0 if success and 1 if failure.

In the preceding example, we want to check if the content of the variable name is the same as Ganesh and ? To check this, we have used the test command. The test will store the result of the comparison in the ? variable.

We can use the following syntax for the preceding test command. In this case, we used [ ] instead of the test command. We've enclosed the expression to be evaluated in square brackets:

$ [[ $name = Ganesh ]]      # Brackets replace the test command
$ echo $?
0

During the evaluation ...