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<?label 9.7. procmail?><html><head><title>procmail (CGI Programming with Perl)</title><link href="../style/style1.css" type="text/css" rel="stylesheet" /><meta name="DC.Creator" content="Scott Guelich, Gunther Birznieks and Shishir Gundavaram" /><meta scheme="MIME" content="text/xml" name="DC.Format" /><meta content="en-US" name="DC.Language" /><meta content="O'Reilly & Associates, Inc." name="DC.Publisher" /><meta scheme="ISBN" name="DC.Source" content="1565924193L" /><meta name="DC.Subject.Keyword" content="stuff" /><meta name="DC.Title" content="CGI Programming with Perl" /><meta content="Text.Monograph" name="DC.Type" /></head><body bgcolor="#ffffff"><img src="gifs/smbanner.gif" alt="Book Home" usemap="#banner-map" border="0" /><map name="banner-map"><area alt="CGI Programming with Perl" href="index.htm" coords="0,0,466,65" shape="rect" /><area alt="Search this book" href="jobjects/fsearch.htm" coords="467,0,514,18" shape="rect" /></map><div class="navbar"><table border="0" width="515"><tr><td width="172" valign="top" align="left"><a href="ch09_06.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0" /></a></td><td width="171" valign="top" align="center"><a href="index.htm">CGI Programming with Perl</a></td><td width="172" valign="top" align="right"><a href="ch10_01.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr></table></div><hr align="left" width="515" /><h2 class="sect1">9.7. procmail</h2><p>If your CGI scripts send out email,<tt class="command">procmail</tt><a name="INDEX-1926" /><a name="INDEX-1927" /> <a name="INDEX-1,928" /> is a veryhandy tool to learn, but it is only available for Unix. If you are ona Unix system and you do not have it, you can download it from<a href="http://www.procmail.org">http://www.procmail.org</a>.<tt class="command">procmail</tt> is a <a name="INDEX-1929" />filtering application that allows youto automatically process email based on virtually any criteria.It's not simple, of course; few powerful tools are. And again,like the other tools presented in this chapter, we won't beable to discuss it in great detail here. Instead, we'll look ata couple configurations that should handle your basic needs. If youwant to learn more, you can find links to several useful resourcesincluding quick-start guides and FAQs at <a href="http://www.iki.fi/era/procmail/">http://www.iki.fi/era/procmail/</a>. Also,don't forget to review the manpage; most of these onlineresources assume you have done this already. You may not normallyenjoy reading manpages, but the <tt class="command">procmail</tt> man pagesare very well written and include numerous examples.</p><p>In order to run <tt class="command">procmail</tt>, you need to<a name="INDEX-1930" />create two files in your home directory(or the home directory of the user whose mail you want to forward).The first file,<em class="filename">.forward</em><a name="INDEX-1931" />, is used by <tt class="command">sendmail</tt>when it delivers mail to your account. That file should be set up toit to direct <tt class="command">sendmail</tt> to run<tt class="command">procmail</tt>, and <tt class="command">procmail</tt> uses the<em class="filename">.procmailrc</em><a name="INDEX-1932" /> file to process the message. It ispossible to have <tt class="command">procmail</tt> set up as the mailtransport agent on your system, instead of<tt class="command">sendmail</tt>; in that case, you do not need the<em class="filename">.forward</em> file. Check with your systemadministrator to see if this is the case.</p><p>Your <em class="filename">.forward</em> file needs to include only thefollowing line:</p><blockquote><pre class="code">"|IFS=' '&&exec /usr/local/bin/procmail -f-||exit 75 #YOUR_USERNAME"</pre></blockquote><p>All of the quotes are necessary, there is only one space between thesingle quotes, you must supply the full path to<tt class="command">procmail</tt>, and you should of course replace<tt class="literal">YOUR_USERNAME</tt> with your own username (or somethingto make this line different from the line in other users'<em class="filename">.forward</em> files).</p><a name="ch09-7-fm2xml" /><div class="sect2"><h3 class="sect2">9.7.1. Autoreply from nobody</h3><p>Now all we need to do is create a <em class="filename">.procmailrc</em>file. The <em class="filename">.procmailrc</em> file contains rules and acommand to execute if the rule matches. In this example, we willcreate only one rule that sends an <a name="INDEX-1933" /><a name="INDEX-1934" />autoreply to allincoming messages. This would be handy if messages sent to the userthat the web server runs as are not redirected. If your web serverruns as a valid user named <em class="emphasis">nobody</em>, you couldplace this in <em class="emphasis">nobody</em>'s home directory.Here is the<a name="INDEX-1935" /><em class="filename">.procmailrc</em> file:</p><blockquote><pre class="code">## This is your email addressEMAIL_ADDRESS=nobody@your-domain.com## Uncomment and edit this line if sendmail isn't at /usr/lib/sendmail#SENDMAIL=/path/to/sendmail## If we get a message, verify that it wasn't sent by a mail daemon## or isn't one of our marked messages. If not, then reply to it using## the contents of the autoreply.txt file as the body of the message## and mark the message by adding an X-Loop header.:0 h* !^FROM_DAEMON* !^X-Loop: $EMAIL_ADDRESS| ( formail -r -A"X-Loop: $EMAIL_ADDRESS"; \ cat "$HOME/autoreply.txt" ) | $SENDMAIL -t## Throw away the messages we're not replying to:0/dev/null</pre></blockquote><p>We'll briefly review what this file does. For more detailedinformation, refer to one of the references listed earlier. First, itsets the <tt class="literal">$EMAIL_ADDRESS</tt> variable to the emailaddress of the account receiving this mail. Next, it should specifythe <a name="INDEX-1936" />path to sendmail if it is somethingother than the path that <tt class="command">procmail</tt> defaults to(typically either <em class="filename">/usr/lib/sendmail</em> or<em class="filename">/usr/sbin/sendmail </em>). The remaining lines arerules.</p><p>All rules start with <tt class="literal">:0</tt>. The first rule also hasan <tt class="literal">h</tt> option indicating that we are only interestedin the message headers of the incoming message; its body will not beincluded in our reply. All the lines that begin with<tt class="literal">*</tt><a name="INDEX-1937" /> <a name="INDEX-1,938" /> are conditions. Basically, anymessage that doesn't look like it was generated by a daemonprocess (this includes bounced mail, mailing lists, etc.) anddoesn't include an<em class="emphasis">X-Loop</em><a name="INDEX-1939" /> header with our email address in itshould be processed by this rule. We'll see why we check forthis header in a moment.</p><p>The message is processed by piping the headers through<tt class="command">formail</tt><a name="INDEX-1940" />, a helper applicationincluded with <tt class="command">procmail</tt>. It constructs a<a name="INDEX-1941" />reply to the given headers and adds an<em class="emphasis">X-Loop</em> header containing our email address. Thereason for adding this to our replies and checking for it in incomingmessages is to avoid endless loops. If our CGI script sends a messagethat bounces (because of an invalid email address, a full account,etc.) and comes back to us, and we automatically reply to it, ourreply will also bounce. This could go on forever, but if we add an<em class="emphasis">X-Loop</em> header, that should be maintained withinreplies so we will know if we see it that we have already replied tothis message and to not process another reply. The check for whetherthe message was generated by a daemon should actually prevent us fromreplying to a bounce, but the daemon check isn't foolproof, sothe <em class="emphasis">X-Loop</em> check is a good way to be safe.</p><p><tt class="command">formail</tt> takes care of the headers for us, and thenwe <tt class="command">cat</tt> the contents of the<em class="filename">autoreply.txt</em> file in our home directory. Youshould create a message in this file appropriate to your site, sayingsomething to the effect that this email address is not used andproviding an alternative email address to the recipient. The finalresults of both the headers and the body are piped to<tt class="command">sendmail,</tt> which reads the headers and delivers ournew reply.</p><p>The remaining rule in the file has no conditions. It catches allmessages that are not processed by the preceding rule, in otherwords, all messages that are sent by daemons or that have alreadybeen replied to. These messages are simply discarded by moving themto <em class="filename">/dev/null</em>.</p></div><a name="ch09-8-fm2xml" /><div class="sect2"><h3 class="sect2">9.7.2. Forwarding to Another User</h3><p>It is also possible to simply<a name="INDEX-1942" /><a name="INDEX-1943" />forward all messages to another user.There are better alternatives than <tt class="command">procmail</tt> fordoing this. Specifically, <tt class="command">sendmail</tt> allows aliasesto be created to redirect mail sent from one email address toanother. However, if you cannot get your system administrator tocreate an alias for you, here is a <em class="filename">.procmail</em>file that forwards all incoming mail to another email address:</p><blockquote><pre class="code">## This is the email address to forward toFORWARD_TO=webmaster@your-domain.com## Uncomment and edit this line if sendmail isn't at /usr/lib/sendmail#SENDMAIL=/path/to/sendmail## Forward all messages:0! $FORWARD_TO</pre></blockquote><p>As you can see, <em class="emphasis">procmail</em> provides you with anumber of options for automatically processing email. In one of ourexamples earlier, we piped the headers of incoming messages through<tt class="command">formail</tt>. We could have just as easily<a name="INDEX-1944" />piped the headers, the body, orthe whole message through a Perl script and thus be able to react toevery email that arrives. For example, you might want to flag ordelete a database record when mail you send to that user is returnedas undeliverable. That's just one example; you can probablythink <a name="INDEX-1945" /> <a name="INDEX-1,946" /> <a name="INDEX-1,947" />of others specific to <a name="INDEX-1,948" /> <a name="INDEX-1,949" />your site.</p></div><hr align="left" width="515" /><div class="navbar"><table border="0" width="515"><tr><td width="172" valign="top" align="left"><a href="ch09_06.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0" /></a></td><td width="171" valign="top" align="center"><a href="index.htm"><img src="../gifs/txthome.gif" alt="Home" border="0" /></a></td><td width="172" valign="top" align="right"><a href="ch10_01.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr><tr><td width="172" valign="top" align="left">9.6. Perl Mailers</td><td width="171" valign="top" align="center"><a href="index/index.htm"><img src="../gifs/index.gif" alt="Book Index" border="0" /></a></td><td width="172" valign="top" align="right">10. Data Persistence</td></tr></table></div><hr align="left" width="515" /><img src="../gifs/navbar.gif" alt="Library Navigation Links" usemap="#library-map" border="0" /><p><font size="-1"><a href="copyrght.htm">Copyright © 2001</a> O'Reilly & Associates. All rights reserved.</font></p><map name="library-map"><area href="../index.htm" coords="1,1,83,102" shape="rect" /><area href="../lnut/index.htm" coords="81,0,152,95" shape="rect" /><area href="../run/index.htm" coords="172,2,252,105" shape="rect" /><area href="../apache/index.htm" coords="238,2,334,95" shape="rect" /><area href="../sql/index.htm" coords="336,0,412,104" shape="rect" /><area href="../dbi/index.htm" coords="415,0,507,101" shape="rect" /><area href="../cgi/index.htm" coords="511,0,601,99" shape="rect" /></map></body></html>⌨️ 快捷键说明
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