Environment Variables

Environment Variables

Variables in LINUX are called environment variables.
By convention their names are in all caps.
Environment variables are not declared; to create one, just use it.
To set an environment variable, use the following syntax:

VAR="This is the value of the variable."
export VAR

You must both set and export it.
Some systems will let you do it in a single statement:

export VAR="This is the value of the variable."

Does yours allow this? (Hint - give it a try!)
Note that there are no spaces around the equal sign - it will not work correctly if you use them.
The quotes allow the variable to be set to the entire string. It causes it to be treated as a single string rather than 7 individual words. Anytime you want to use a string, put in in quotes (more on this later!)
To access the value of the variable, but a $ in front of it. For instance, this uses the echo command to display the value of the environment variable.

echo $VAR

What is the expected output?
LINUX has a number of built-in environment variables. These are set automatically by the system when you log in. Some are listed below. Does your LINUX support all of these?

HOME	- set to your home directory.
LOGNAME	- set to your login name.
OS_TYPE	- set to your operating system (this is different for the different UNIX/LINUX flavors). In some systems the variable is OS.
PATH	- set to a list of directories where commands can be found (more on this later).
SHELL	- set to your login shell.
TERM	- set to your terminal type.

Remember, you can also set environment variables yourself.
Use the env command to see your current environment variables.