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pcre_table(5) - pcre_table - format of Postfix PCRE tables - man 5 pcre_table

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PCRE_TABLE(5)                                                    PCRE_TABLE(5)



NAME
       pcre_table - format of Postfix PCRE tables

SYNOPSIS
       postmap -fq "string(3,n)" pcre:/etc/postfix/filename

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

DESCRIPTION
       The  Postfix  mail(1,8) system uses optional tables for address rewriting or
       mail(1,8) routing. These tables are usually in(1,8) dbm or db format.

       Alternatively, lookup tables can be specified in(1,8) Perl Compatible  Regu-
       lar  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(1,5) -m" command.

       To test lookup tables, use the "postmap -fq" command  as  described  in(1,8)
       the SYNOPSIS above.

TABLE FORMAT
       The general form of a PCRE table is:

       /pattern/flags result
              When  pattern  matches  the  input string(3,n), use the corresponding
              result value.

       !/pattern/flags result
              When pattern does not match the input  string(3,n),  use  the  corre-
              sponding result value.

       if(3,n) /pattern/flags

       endif  Match  the  input  string(3,n)  against  the  patterns between if(3,n) and
              endif, if(3,n) and only if(3,n) the input string(3,n) also matches pattern. The
              if(3,n)..endif can nest.

              Note: do not prepend whitespace to patterns inside if(3,n)..endif.

       if(3,n) !/pattern/flags

       endif  Match  the  input  string(3,n)  against  the  patterns between if(3,n) and
              endif, if(3,n) and only if(3,n) the input string(3,n) does not  match  pattern.
              The if(3,n)..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 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)
              Toggles the PCRE_MULTILINE flag. When this flag is on, the ^ and
              $  metacharacters match immediately after and immediately before
              a newline character, respectively, in(1,8) 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  ver-
              sions  prior to 2.0, The flag is off by default, which is incon-
              venient for multi-line message header matching.

       x (default: off)
              Toggles the pcre extended flag. When this flag is on, whitespace
              in(1,8)  the pattern (other than in(1,8) 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(3,n) which  is  being  searched
              (the  "subject  string(3,n)").  This  effect  can also be achieved by
              appropriate constructs in(1,8) the pattern itself.

       E (default: off)
              Toggles the PCRE_DOLLAR_ENDONLY flag. When this flag is on, a  $
              metacharacter in(1,8) 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(3,n) it is a newline character
              (but not before any other  newline  characters).  This  flag  is
              ignored if(3,n) 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(3,n) followed by "?".  This flag can also set(7,n,1 builtins) by a  (?U)  modifier
              within the pattern.

       X (default: off)
              Toggles  the  PCRE_EXTRA  flag.  When this flag is on, any back-
              slash in(1,8) a pattern that is followed by a letter that has no spe-
              cial  meaning causes an error(8,n), thus reserving these combinations
              for future expansion.

SEARCH ORDER
       Patterns are applied in(1,8) the order as specified in(1,8) 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(3,n) is an entire client hostname, an entire client
       IP  address, or an entire mail(1,8) address.  Thus, no parent domain or par-
       ent network search is done, and user@domain mail(1,8) addresses are not bro-
       ken  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(3,n)  is  possible using the conventional perl syntax ($1, $2, etc.).
       The macros in(1,8) the result string(3,n) may need to be written as ${n} or  $(n)
       if(3,n) 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(1,8) - this is just an example).
       /^(friend@(?!my\.domain$).*)$/  550 Stick this in(1,8) your pipe(2,8) $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(2,n) mail(1,8) 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(1,3,5) 3.
       ~^[[:alnum:]+/]{60,}$~          OK

       # Put your own body patterns here.

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

README FILES
       Use  "postconf(1,5) readme_directory" or "postconf(1,5) 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)

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