fied at run time by specifying <i>environment variables</i>. The variables have names which begin with <code>PGPLOT_</code>.</p>

<p>In UNIX systems, environment variables can be defined using the shell. For the bash, bourne (sh), or korn (ksh) shell, use commands like the following:</p>

<pre>PGPLOT_DIR="/usr/local/pgplot"; export PGPLOT_DIR
</pre>

<p>For the c-shell and tcsh, use</p>

<pre>setenv PGPLOT_DIR "/usr/local/pgplot/"
</pre>

<p>Note that the names of PGPLOT environment variables are specified 