Provided by: postfix_2.2.10-1_i386 bug

NAME

       pcre_table - format of Postfix PCRE tables

SYNOPSIS

       postmap -fq "string" pcre:/etc/postfix/filename

       postmap -fq - pcre:/etc/postfix/filename <inputfile

DESCRIPTION

       The  Postfix  mail system uses optional tables for address rewriting or
       mail routing. These tables are usually in dbm or db format.

       Alternatively, lookup  tables  can  be  specified  in  Perl  Compatible
       Regular Expression form. In this case, each input is compared against a
       list of patterns, and when a match is found the corresponding result is
       returned.

       To  find  out  what types of lookup tables your Postfix system supports
       use the "postconf -m" command.

       To test lookup tables, use the "postmap -fq" command  as  described  in
       the SYNOPSIS above.

TABLE FORMAT

       The general form of a PCRE table is:

       /pattern/flags result
              When  pattern  matches  the  input string, use the corresponding
              result value.

       !/pattern/flags result
              When  pattern  does  not  match  the  input  string,   use   the
              corresponding result value.

       if /pattern/flags

       endif  Match  the  input  string  against  the  patterns between if and
              endif, if and only if the input string also matches pattern. The
              if..endif can nest.

              Note: do not prepend whitespace to patterns inside if..endif.

       if !/pattern/flags

       endif  Match  the  input  string  against  the  patterns between if and
              endif, if and only if the input string does not  match  pattern.
              The if..endif can nest.

       blank lines and comments
              Empty  lines and whitespace-only lines are ignored, as are lines
              whose first non-whitespace character is a ‘#’.

       multi-line text
              A logical line starts with  non-whitespace  text.  A  line  that
              starts with whitespace continues a logical line.

       Each   pattern  is  a  perl-like  regular  expression.  The  expression
       delimiter can be any character, except whitespace  or  characters  that
       have  special  meaning  (traditionally the forward slash is used).  The
       regular expression can contain whitespace.

       By default, matching is case-insensitive, and newlines are not  treated
       as  special  characters. The behavior is controlled by flags, which are
       toggled by appending one or more of the following characters after  the
       pattern:

       i (default: on)
              Toggles  the case sensitivity flag. By default, matching is case
              insensitive.

       m (default: off)
              Toggles the PCRE_MULTILINE flag. When this flag is on, the ^ and
              $  metacharacters match immediately after and immediately before
              a newline character, respectively, in addition  to  matching  at
              the start and end of the subject string.

       s (default: on)
              Toggles  the  PCRE_DOTALL  flag.  When  this  flag  is on, the .
              metacharacter  matches  the  newline  character.  With   Postfix
              versions  prior  to  2.0,  The  flag is off by default, which is
              inconvenient for multi-line message header matching.

       x (default: off)
              Toggles the pcre extended flag. When this flag is on, whitespace
              in  the pattern (other than in a character class) and characters
              between a # outside a  character  class  and  the  next  newline
              character  are  ignored.  An  escaping  backslash can be used to
              include a whitespace or # character as part of the pattern.

       A (default: off)
              Toggles the PCRE_ANCHORED flag.   When  this  flag  is  on,  the
              pattern  is  forced to be "anchored", that is, it is constrained
              to match only at the start of the string which is being searched
              (the  "subject  string").  This  effect  can also be achieved by
              appropriate constructs in the pattern itself.

       E (default: off)
              Toggles the PCRE_DOLLAR_ENDONLY flag. When this flag is on, a  $
              metacharacter  in  the  pattern  matches  only at the end of the
              subject  string.  Without  this  flag,  a  dollar  also  matches
              immediately  before  the  final  character  if  it  is a newline
              character (but not before any other  newline  characters).  This
              flag is ignored if PCRE_MULTILINE flag is set.

       U (default: off)
              Toggles  the  ungreedy matching flag.  When this flag is on, the
              pattern  matching  engine  inverts  the  "greediness"   of   the
              quantifiers  so  that they are not greedy by default, but become
              greedy if followed by "?".  This flag can also  set  by  a  (?U)
              modifier within the pattern.

       X (default: off)
              Toggles  the  PCRE_EXTRA  flag.   When  this  flag  is  on,  any
              backslash in a pattern that is followed by a letter that has  no
              special   meaning   causes   an   error,  thus  reserving  these
              combinations for future expansion.

SEARCH ORDER

       Patterns are applied in the order as specified in the  table,  until  a
       pattern is found that matches the input string.

       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, and user@domain mail addresses  are  not
       broken up into their user and domain constituent parts, nor is user+foo
       broken up into user and foo.

TEXT SUBSTITUTION

       Substitution of substrings from the matched expression into the  result
       string  is  possible using the conventional perl syntax ($1, $2, etc.).
       The macros in the result string may need to be written as ${n} or  $(n)
       if they aren’t followed by whitespace.

       Note: since negated patterns (those preceded by !) return a result when
       the expression does not match,  substitutions  are  not  available  for
       negated patterns.

EXAMPLE SMTPD ACCESS MAP

       # Protect your outgoing majordomo exploders
       /^(?!owner-)(.*)-outgoing@(.*)/ 550 Use ${1}@${2} instead

       # Bounce friend@whatever, except when whatever is our domain (you would
       # be better just bouncing all friend@ mail - this is just an example).
       /^(friend@(?!my\.domain$).*)$/  550 Stick this in your pipe $1

       # A multi-line entry. The text is sent as one line.
       #
       /^noddy@my\.domain$/
        550 This user is a funny one. You really don’t want to send mail to
        them as it only makes their head spin.

EXAMPLE HEADER FILTER MAP

       /^Subject: make money fast/     REJECT
       /^To: friend@public\.com/       REJECT

EXAMPLE BODY FILTER MAP

       # First skip over base 64 encoded text to save CPU cycles.
       # Requires PCRE version 3.
       ~^[[:alnum:]+/]{60,}$~          OK

       # Put your own body patterns here.

SEE ALSO

       postmap(1), Postfix lookup table manager
       postconf(5), configuration parameters
       regexp_table(5), format of POSIX regular expression tables

README FILES

       Use  "postconf readme_directory" or "postconf html_directory" to locate
       this information.
       DATABASE_README, Postfix lookup table overview

AUTHOR(S)

       The PCRE table lookup code was originally written by:
       Andrew McNamara
       andrewm@connect.com.au
       connect.com.au Pty. Ltd.
       Level 3, 213 Miller St
       North Sydney, NSW, Australia

       Adopted and adapted by:
       Wietse Venema
       IBM T.J. Watson Research
       P.O. Box 704
       Yorktown Heights, NY 10598, USA

                                                                 PCRE_TABLE(5)