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 of expressions by test, we can even use wildcard expressions:

$ [[ $name = [Gg]????? ]]
$ echo $?
0

Therefore, we can either use the test command or square brackets for checking or evaluating expressions. Since word splitting will be performed...