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PCRE_TABLE(5)                                                    PCRE_TABLE(5)

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 Com-
       patible 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  sys-
       tem 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 cor-
              responding 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.

              This feature is available in Postfix 2.1 and later.

       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.

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

              This feature is available in Postfix 2.1 and later.

       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 logi-
              cal line.

       Each  pattern  is  a  perl-like  regular  expression.  The
       expression  delimiter  can be any character, except white-
       space or characters that have special meaning  (tradition-
       ally  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 con-
       trolled 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  immedi-
              ately before the final character if it is a newline
              character (but not before any other newline charac-
              ters).  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 fol-
              lowed 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 expan-
              sion.

SEARCH ORDER
       Patterns  are applied in the order as specified in the ta-
       ble, 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  [email protected] 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.);  specify $$ to produce a $
       character as output.  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-)(.*)[email protected](.*)/ 550 Use ${1}@${2} instead

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

       # A multi-line entry. The text is sent as one line.
       #
       /^[email protected]\.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: [email protected]\.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
       DATABASE_README, Postfix lookup table overview

AUTHOR(S)
       The PCRE table lookup code was originally written by:
       Andrew McNamara
       [email protected]
       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)