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8<title>Postfix PCRE Support</title>
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16<h1><img src="postfix-logo.jpg" width="203" height="98" ALT="">Postfix PCRE Support</h1>
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19
20<h2>PCRE (Perl Compatible Regular Expressions) map support</h2>
21
22<p> The optional "pcre" map type allows you to specify regular
23expressions with the PERL style notation such as \s for space and
24\S for non-space. The main benefit, however, is that pcre lookups
25are often faster than regexp lookups. This is because the pcre
26implementation is often more efficient than the POSIX regular
27expression implementation that you find on many systems. </p>
28
29<p> A description of how to use pcre tables, including examples,
30is given in the <a href="pcre_table.5.html">pcre_table(5)</a> manual page. Information about PCRE
31itself can be found at <a href="http://www.pcre.org/">http://www.pcre.org/</a>. </p>
32
33<h2>Building Postfix with PCRE support</h2>
34
35<p> These instructions assume that you build Postfix from source
36code as described in the <a href="INSTALL.html">INSTALL</a> document. Some modification may
37be required if you build Postfix from a vendor-specific source
38package.  </p>
39
40<p> Note: to use pcre with Debian GNU/Linux's Postfix, all you
41need is to install the postfix-pcre package and you're done.  There
42is no need to recompile Postfix. </p>
43
44<p> In some future, Postfix will have a plug-in interface for adding
45map types. Until then, you need to compile PCRE support into Postfix.
46</p>
47
48<p> First of all, you need the PCRE library (Perl Compatible Regular
49Expressions), which can be obtained from: </p>
50
51<blockquote>
52<a href="ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/">ftp://ftp.csx.cam.ac.uk/pub/software/programming/pcre/</a>.
53</blockquote>
54
55<p> NOTE: pcre versions prior to 2.06 cannot be used. </p>
56
57<p> In order to build Postfix with PCRE support you need to add
58-DHAS_PCRE and a -I for the PCRE include file to CCARGS, and add
59the path to the PCRE library to AUXLIBS, for example: </p>
60
61<blockquote>
62<pre>
63make -f Makefile.init makefiles \
64    "CCARGS=-DHAS_PCRE -I/usr/local/include" \
65    "AUXLIBS=-L/usr/local/lib -lpcre"
66</pre>
67</blockquote>
68
69<p> Solaris needs run-time path information too: </p>
70
71<blockquote>
72<pre>
73make -f Makefile.init makefiles \
74    "CCARGS=-DHAS_PCRE -I/usr/local/include" \
75    "AUXLIBS=-L/usr/local/lib -R/usr/local/lib -lpcre"
76</pre>
77</blockquote>
78
79<h2>Things to know</h2>
80
81<ul>
82
83<li> <p> When Postfix searches a <a href="pcre_table.5.html">pcre</a>: or <a href="regexp_table.5.html">regexp</a>: lookup table,
84each pattern is applied to the entire input string. Depending on
85the application, that string is an entire client hostname, an entire
86client IP address, or an entire mail address. Thus, no parent domain
87or parent network search is done, "user@domain" mail addresses are
88not broken up into their user and domain constituent parts, and
89"user+foo" is not broken up into user and foo.  </p>
90
91<li> <p> Regular expression tables such as <a href="pcre_table.5.html">pcre</a>: or <a href="regexp_table.5.html">regexp</a>: are
92not allowed to do $number substitution in lookup results that can
93be security sensitive: currently, that restriction applies to the
94local <a href="aliases.5.html">aliases(5)</a> database or the <a href="virtual.8.html">virtual(8)</a> delivery agent tables.
95</p>
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