bionic (5) pcre_table.5.gz

Provided by: postfix-pcre_3.3.0-1ubuntu0.4_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).

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-alphanumerical
       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 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
              expansion.

       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.

       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

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

                                                                                                   PCRE_TABLE(5)