Using the Shell

As you have been reading this book, you've been interacting with the shell
already. The shell is the program that reads your commands and then does
what you ask it to. In this chapter, you explore the shell in greater
detail, with a special eye towards customizing the shell to work as you
want it to.

Environment Variables

Every process has an environment associated with it. An environment is a
collection of environment variables. A variable is a changeable value with
a fixed name. For example, the name EMAIL could refer to the value
joe@nowhere.com. The value can vary; EMAIL could also refer to
jane@somewhere.com.

Because your shell is a process like any other, it has an environment. You
can view your shell's environment by entering the printenv command.

Figure 6.1: Sample printenv output
\begin{figure}\par\par\begin{list}{}{ \setlength{\rightmargin}{\leftmargin}
\ra... ...ables}\index{shells!environments}
\par\_=/usr/bin/printenv\end{list}\end{figure}

Figure 6.1 on page [*] has some sample output from printenv. On your
system, the output will be different but similar.

Environment variables are one way to configure the system. For example,
the EDITOR variable lets you select your preferred editor for posting