1<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN" 2 "http://www.w3.org/TR/html4/loose.dtd"> 3 4<html> 5 6<head> 7 8<title>Postfix PCRE Support</title> 9 10<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 11 12</head> 13 14<body> 15 16<h1><img src="postfix-logo.jpg" width="203" height="98" ALT="">Postfix PCRE Support</h1> 17 18<hr> 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 pcre_table(5) manual page. Information about PCRE 31itself can be found at http://www.pcre.org/. </p> 32 33<h2>Using Postfix packages with PCRE support</h2> 34 35<p> To use pcre with Debian GNU/Linux's Postfix, or with Fedora or 36RHEL Postfix, all you 37need is to install the postfix-pcre package and you're done. There 38is no need to recompile Postfix. </p> 39 40<h2>Building Postfix from source with PCRE support</h2> 41 42<p> These instructions assume that you build Postfix from source 43code as described in the INSTALL document. </p> 44 45<p> To build Postfix from source with pcre support, you need a pcre 46library. Install a vendor package, or download the source code from 47locations in https://www.pcre.org/ and build that yourself. 48 49<p> Postfix can build with the pcre2 library or the legacy pcre 50library. It's probably easiest to let the Postfix build procedure 51pick one. The following commands will first discover if the pcre2 52library is installed, and if that is not available, will discover 53if the legacy pcre library is installed. </p> 54 55<blockquote> 56<pre> 57$ make -f Makefile.init makefiles 58$ make 59</pre> 60</blockquote> 61 62<p> To build Postfix explicitly with a pcre2 library (Postfix 3.7 63and later): </p> 64 65<blockquote> 66<pre> 67$ make -f Makefile.init makefiles \ 68 "CCARGS=-DHAS_PCRE=2 `pcre2-config --cflags`" \ 69 "AUXLIBS_PCRE=`pcre2-config --libs8`" 70$ make 71</pre> 72</blockquote> 73 74<p> To build Postfix explicitly with a legacy pcre library (all 75Postfix versions): </p> 76 77<blockquote> 78<pre> 79$ make -f Makefile.init makefiles \ 80 "CCARGS=-DHAS_PCRE=1 `pcre-config --cflags`" \ 81 "AUXLIBS_PCRE=`pcre-config --libs`" 82$ make 83</pre> 84</blockquote> 85 86<p> Postfix versions before 3.0 use AUXLIBS instead of AUXLIBS_PCRE. 87With Postfix 3.0 and later, the old AUXLIBS variable still supports 88building a statically-loaded PCRE database client, but only the new 89AUXLIBS_PCRE variable supports building a dynamically-loaded or 90statically-loaded PCRE database client. </p> 91 92<blockquote> 93 94<p> Failure to use the AUXLIBS_PCRE variable will defeat the purpose 95of dynamic database client loading. Every Postfix executable file 96will have PCRE library dependencies. And that was exactly 97what dynamic database client loading was meant to avoid. </p> 98 99</blockquote> 100 101<h2>Things to know</h2> 102 103<ul> 104 105<li> <p> When Postfix searches a pcre: or regexp: lookup table, 106each pattern is applied to the entire input string. Depending on 107the application, that string is an entire client hostname, an entire 108client IP address, or an entire mail address. Thus, no parent domain 109or parent network search is done, "user@domain" mail addresses are 110not broken up into their user and domain constituent parts, and 111"user+foo" is not broken up into user and foo. </p> 112 113<li> <p> Regular expression tables such as pcre: or regexp: are 114not allowed to do $number substitution in lookup results that can 115be security sensitive: currently, that restriction applies to the 116local aliases(5) database or the virtual(8) delivery agent tables. 117</p> 118 119</ul> 120 121</body> 122 123</html> 124
