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<h3>Reading Options and Environment Variables</h3>
<p>When the interpreter starts, command-line options are placed in the list <tT CLAss="monofont">sys.argv</tt>. The first element is the name of the program. Subsequent elements are the options presented on the command line <I>after</I> the program name. The following program shows how to access command-line options:</P>
<Pre>
# printopt.py
# Print all of the command-line options
import sys
for i in range(len(sys.argv)):
print "sys.argv[%d] = %s" % (i, sys.argv[i]) </prE>
<P>Running the program produces the following:</P>
<Pre>
% python printopt.py foo bar -p
sys.argv[0] = printopt.py
sys.argv[1] = foo
sys.argv[2] = bar
sys.argv[3] = -p
% </pre>
<p>Environment variables are accessed in the dictionary <tt class="monofont">os.environ</tt>. For example:</p>
<pre>
import os
path = os.environ["PATH"]
user = os.environ["USER"]
editor = os.environ["EDITOR"]
... etc ... </pRe>
<p>To modify the environment variables, set the <Tt clAss="monofont">os.environ</tt> variable. Alternatively, you can use the <Tt clASS="monofont">os.putenv()</Tt> function. For example:</p>
<prE>
os.environ["FOO"] = "BAR"
os.putenv("FOO","BAR") </PRE>
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<P><TABLE width="100%" border=0><TR valign="top"><TD><font size=1 color="#C0C0C0"><br></font></TD><TD align=right><font size=1 color="#C0C0C0">Last updated on 3/28/2002<br>Python Essential Reference, Second Edition, © 2002 New Riders Publishing</font></TD></TR></TABLE></P>
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