Provided by: postfix-pcre_3.7.4-2build1_amd64 bug

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

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)