phpman > man > pcre_table(5)

PCRE_TABLE(5)                            File Formats Manual                           PCRE_TABLE(5)



NAME
       pcre_table - format of Postfix PCRE tables

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

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

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

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

DESCRIPTION
       The  Postfix  mail system uses optional tables for address rewriting, mail routing, or access
       control. 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. When a match is found, the cor‐
       responding result is returned and the search is terminated.

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

       To  test  lookup tables, use the "postmap -q" command as described in the SYNOPSIS above. Use
       "postmap -hmq - <file"  for  header_checks(5)  patterns,  and  "postmap  -bmq  -  <file"  for
       body_checks(5) (Postfix 2.6 and later).

COMPATIBILITY
       With  Postfix  version  2.2  and earlier specify "postmap -fq" to query a table that contains
       case sensitive patterns. Patterns are case insensitive by default.

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  If the input string matches /pattern/, then match that input string against  the  pat‐
              terns between if and endif.  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  If the input string does not match /pattern/, then match that input string against the
              patterns between if and endif. 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-white‐
              space 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  non-al‐
       phanumerical character, except whitespace 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 controlled by flags, which are toggled by appending one or more of the fol‐
       lowing 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  characters  in  the
              pattern  (other than in a character class) are ignored.  To include a whitespace char‐
              acter as part of the pattern, escape it with backslash.

              Note: do not use #comment after patterns.

       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  appro‐
              priate 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 (text that matches patterns inside "()") from the matched expres‐
       sion into the result string is requested with $1, $2, etc.; specify $$ to produce a $ charac‐
       ter  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-)(.*)-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 AT connect.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

       Wietse Venema
       Google, Inc.
       111 8th Avenue
       New York, NY 10011, USA



                                                                                       PCRE_TABLE(5)