Shell environment variables are used for several purposes, from storing data, storing software configurations, set terminal settings, and changing shell environment. The environment variables are normally set at boot time, or by different software as required. One way of setting environmental variables is from the command line.
List all variables on terminal
this will print all the variable that you have
Show one variable at a time
The amount of these variables can become a very long list and locating one specific variable can become a tough task. Fortunately Linux allows us to display the value of one shell variable by using the
echo command along with the name of the variable. This makes the task very easy.
Add or change a variable
To add or modify an environment variable, we can use the export command followed by the name of the variable and the values that go with it.
Note, however, that this will only work for the current shell session. It won't be available in any other terminals.