exporting variable in Shell

You can create your own environmental variables in shell

It is very simple just type export followed by your variable and the value.

For exporting a variable gg

export gg="hello"

echo $gg
hello
you will be able to see the content of the variable gg - "hello"

But it stays untill reboot.Once you reboot you have to set the variable again.

To make it permanent you can add it to /etc/profile to make the change visible for all users using your system or you can add the change to the ~/.bash_rc to make the change visible only for your shell.