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diff --git a/README_FILES/PCRE_README b/README_FILES/PCRE_README new file mode 100644 index 0000000..6dffb4b --- /dev/null +++ b/README_FILES/PCRE_README @@ -0,0 +1,78 @@ +PPoossttffiixx PPCCRREE SSuuppppoorrtt + +------------------------------------------------------------------------------- + +PPCCRREE ((PPeerrll CCoommppaattiibbllee RReegguullaarr EExxpprreessssiioonnss)) mmaapp ssuuppppoorrtt + +The optional "pcre" map type allows you to specify regular expressions with the +PERL style notation such as \s for space and \S for non-space. The main +benefit, however, is that pcre lookups are often faster than regexp lookups. +This is because the pcre implementation is often more efficient than the POSIX +regular expression implementation that you find on many systems. + +A description of how to use pcre tables, including examples, is given in the +pcre_table(5) manual page. Information about PCRE itself can be found at http:/ +/www.pcre.org/. + +UUssiinngg PPoossttffiixx ppaacckkaaggeess wwiitthh PPCCRREE ssuuppppoorrtt + +To use pcre with Debian GNU/Linux's Postfix, or with Fedora or RHEL Postfix, +all you need is to install the postfix-pcre package and you're done. There is +no need to recompile Postfix. + +BBuuiillddiinngg PPoossttffiixx ffrroomm ssoouurrccee wwiitthh PPCCRREE ssuuppppoorrtt + +These instructions assume that you build Postfix from source code as described +in the INSTALL document. + +To build Postfix from source with pcre support, you need a pcre library. +Install a vendor package, or download the source code from locations in https:/ +/www.pcre.org/ and build that yourself. + +Postfix can build with the pcre2 library or the legacy pcre library. It's +probably easiest to let the Postfix build procedure pick one. The following +commands will first discover if the pcre2 library is installed, and if that is +not available, will discover if the legacy pcre library is installed. + + $ make -f Makefile.init makefiles + $ make + +To build Postfix explicitly with a pcre2 library (Postfix 3.7 and later): + + $ make -f Makefile.init makefiles \ + "CCARGS=-DHAS_PCRE=2 `pcre2-config --cflags`" \ + "AUXLIBS_PCRE=`pcre2-config --libs8`" + $ make + +To build Postfix explicitly with a legacy pcre library (all Postfix versions): + + $ make -f Makefile.init makefiles \ + "CCARGS=-DHAS_PCRE=1 `pcre-config --cflags`" \ + "AUXLIBS_PCRE=`pcre-config --libs`" + $ make + +Postfix versions before 3.0 use AUXLIBS instead of AUXLIBS_PCRE. With Postfix +3.0 and later, the old AUXLIBS variable still supports building a statically- +loaded PCRE database client, but only the new AUXLIBS_PCRE variable supports +building a dynamically-loaded or statically-loaded PCRE database client. + + Failure to use the AUXLIBS_PCRE variable will defeat the purpose of dynamic + database client loading. Every Postfix executable file will have PCRE + library dependencies. And that was exactly what dynamic database client + loading was meant to avoid. + +TThhiinnggss ttoo kknnooww + + * When Postfix searches a pcre: or regexp: lookup table, each pattern is + applied to the entire input string. Depending on the application, that + string is an entire client hostname, an entire client IP address, or an + entire mail address. Thus, no parent domain or parent network search is + done, "user@domain" mail addresses are not broken up into their user and + domain constituent parts, and "user+foo" is not broken up into user and + foo. + + * Regular expression tables such as pcre: or regexp: are not allowed to do + $number substitution in lookup results that can be security sensitive: + currently, that restriction applies to the local aliases(5) database or the + virtual(8) delivery agent tables. + |