PCRE_TABLE(5)                                       PCRE_TABLE(5)
NAME
       pcre_table - format of Postfix PCRE tables
SYNOPSIS
       pcre:/etc/postfix/filename
       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 or mail routing. These tables are usually in dbm
       or  db  format. Alternatively, lookup tables can be speci-
       fied in Perl Compatible Regular Expression form.
       To find out what types of lookup tables your Postfix  sys-
       tem supports use the postconf -m command.
       To   test  lookup  tables,  use  the  postmap  command  as
       described in the SYNOPSIS above.
       The general form of a PCRE table is:
       /pattern/flags result
              When pattern matches a search string, use the  cor-
              responding result value.
       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  logi-
              cal line.
       if /pattern/flags
       endif  Match   the  search  string  against  the  patterns
              between if and endif, if and  only  if  the  search
              string matches pattern. The if..endif can nest.
              Note:  do not prepend whitespace to patterns inside
              if..endif.
       Each  pattern  is  a  perl-like  regular  expression.  The
       expression  delimiter can be any character, except whites-
       pace 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 con-
       trolled 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 20020528,  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  in  the  pattern  (other than in a
              character class) and characters between a # outside
              a  character  class  and the next newline character
              are ignored. An escaping backslash can be  used  to
              include  a whitespace or # character as part of the
              pattern.
       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  immedi-
              ately before the final character if it is a newline
              character (but not before any other newline charac-
              ters).  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 fol-
              lowed 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.
       Each  pattern  is applied to the entire lookup key 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.
       Patterns  are  applied  in  the  order as specified in the
       table, until a pattern is found that  matches  the  search
       string.
       Substitution  of  substrings  from  the matched expression
       into the result string is possible using the  conventional
       perl  syntax  ($1,  $2,  etc.).   The macros in the result
       string may need to be written as  ${n}  or  $(n)  if  they
       aren't followed by whitespace.
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 $0
       # A multi-line entry. The text is sent as one line.
       #
       /^noddy@my\.domain$/
        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
       regexp_table(5) format of POSIX regular expression tables
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)