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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

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 corresponding 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.

COMPATIBILITY
       With Postfix version 2.2 and earlier specify "postmap -fq" to query a table that contains case sensitive  pat‐
       terns. 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  Match the input string against the patterns between if and endif, if and only if that same 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 that same 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

       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 character 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 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 expan‐
              sion.

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  con‐
       stituent 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 conven‐
       tional 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, substi‐
       /^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
       [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)