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 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. Use "postmap -hmq - <file" for header_checks(5)
       patterns, and "postmap -bmq - <file" for body_checks(5) (Postfix 2.6
       and later).

       This driver can be built with the pcre2 library (Postfix 3.7 and
       later), or with the legacy pcre library (all Postfix versions).

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 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.

       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-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-alphanumeric 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 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 the pcre MULTILINE flag is set.

       U (default: off)
              Toggles the pcre UNGREEDY 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.

              This feature is not supported with PCRE2.

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 expression into the result string is requested with
       $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.  This feature does not support
       pcre2 substring names.

       Note: since negated patterns (those preceded by !) return a result when
       the expression does not match, substitutions are not available for
       negated patterns.

INLINE SPECIFICATION
       The contents of a table may be specified in the table name (Postfix 3.7
       and later).  The basic syntax is:

       main.cf:
           parameter = .. pcre:{ { rule-1 }, { rule-2 } .. } ..

       master.cf:
           .. -o { parameter = .. pcre:{ { rule-1 }, { rule-2 } .. } .. } ..

       Postfix ignores whitespace after '{' and before '}', and writes each
       rule as one text line to an in-memory file:

       in-memory file:
           rule-1
           rule-2
           ..

       Postfix parses the result as if it is a file in /etc/postfix.

       Note: if an inlined rule contains $, specify $$ to keep Postfix from
       trying to do $name expansion as it evaluates a parameter value.

       Note: when using $name inside an inlined pattern, use \Q$name\E to
       disable metacharacters such as '.' in the $name expansion. Otherwise,
       the pattern may have unexpected matches.

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

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

                                                                 PCRE_TABLE(5)