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PCRE_TABLE(5)                                                                                  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 sensi-
       tive 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  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
              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-alphanumeri-cal non-alphanumerical
       cal 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  charac-ters characters
       ters 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 imme-diately immediately
              diately after and immediately before a newline character, respectively, in addition to  match-ing matching
              ing 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  inconve-nient inconvenient
              nient 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 pat-tern pattern
              tern 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 imme-diately immediately
              diately before the final character if it is a newline character (but not before any other new-line newline
              line 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 fol-lowed followed
              lowed by a letter that has no special meaning causes an error, thus reserving  these  combina-tions combinations
              tions 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 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-)(.*)-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@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)