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pcre_table


SYNOPSIS

       pcre:/etc/postfix/filename

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

       postmap -q - 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.  Alterna-
       tively,  lookup  tables  can  be  specified  in Perl Compatible Regular
       Expression form.

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

       To test lookup tables, use the postmap command as described in the SYN-
       OPSIS above.

       The general form of a PCRE table is:

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

       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.

       if /pattern/flags

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

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

       Each  pattern  is a perl-like regular expression. The expression delim-
       iter 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)

       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 char-
              acter  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  pat-
              tern  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 sub-
              ject string. Without this flag, a dollar  also  matches  immedi-
              ately  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  quanti-
              fiers  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 back-
              slash in a pattern that is followed by a letter that has no spe-
              cial  meaning causes an error, thus reserving these combinations
              for future expansion.

       Each pattern is applied to the entire lookup key 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.

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

       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.


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
       /^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

       regexp_table(5) format of POSIX regular expression tables


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)

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