How Linux Works

Environment and Shell Variables

The shell can store temporary variables, called shell variables, that store the values of text strings. Shell variables are very useful for keeping track of state in scripts, and some shell variables control the way the shell behaves (for example, the PS1 variable controls the prompt). To assign a value to a shell variable, use the equal sign (=):

STUFF=blah

The preceding example sets the value of the variable named STUFF to blah. To access this variable, use $STUFF (for example, try running echo $STUFF).

An environment variable is like a shell variable, but is not specific to the shell. All programs on Unix systems have environment variable storage. The difference that you will notice is that the operating system ...