postfix-master/PCRE_README.html

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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
  23 expressions with the PERL style notation such as \s for space and
  24 \S for non-space. The main benefit, however, is that pcre lookups
  25 are often faster than regexp lookups. This is because the pcre
  26 implementation is often more efficient than the POSIX regular
  27 expression implementation that you find on many systems. </p>
  28
  29 <p> A description of how to use pcre tables, including examples,
  30 is given in the <a href="pcre_table.5.html">pcre_table(5)</a> manual page. Information about PCRE
  31 itself 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
  36 code as described in the <a href="INSTALL.html">INSTALL</a> document. Some modification may
  37 be required if you build Postfix from a vendor-specific source
  38 package.  </p>
  39
  40 <p> Note: to use pcre with Debian GNU/Linux's Postfix, all you
  41 need is to install the postfix-pcre package and you're done.  There
  42 is no need to recompile Postfix. </p>
  43
  44 <p> In some future, Postfix will have a plug-in interface for adding
  45 map 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
  49 Expressions), 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
  59 the path to the PCRE library to AUXLIBS, for example: </p>
  60
  61 <blockquote>
  62 <pre>
  63 make -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>
  73 make -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,
  84 each pattern is applied to the entire input string. Depending on
  85 the application, that string is an entire client hostname, an entire
  86 client IP address, or an entire mail address. Thus, no parent domain
  87 or parent network search is done, "user@domain" mail addresses are
  88 not 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
  92 not allowed to do $number substitution in lookup results that can
  93 be security sensitive: currently, that restriction applies to the
  94 local <a href="aliases.5.html">aliases(5)</a> database or the <a href="virtual.8.html">virtual(8)</a> delivery agent tables.
  95 </p>
  96
  97 </ul>
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