Understanding variables

Let's learn about creating variables in a shell.

Declaring variables in Linux is very easy. We just need to use the variable name and initialize it with the required content.

$ person="Ganesh Naik"

To get the content of the variable, we need to add the prefix $ before the variable, for example:

    $ echo person
    person
    $ echo $person
    Ganesh Naik
 

The unset command can be used to delete the declared variable:

$ a=20$ echo $a$ unset a

The unset command will clear or remove the variable from the shell environment as well.

Here, the set command will show all variables declared in the shell:

$ person="Ganesh Naik"$ echo $person$ set

Here, using the declare command with the -x option will make it an environmental or global variable. We will find out more about environmental variables in the next section.

$ declare -x variable=value

Here, the env command will display all environmental variables:

$ env

Whenever we declare a variable, that variable will be available in the...