1REGEXP_TABLE(5)               File Formats Manual              REGEXP_TABLE(5)
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NAME

6       regexp_table - format of Postfix regular expression tables
7

SYNOPSIS

9       postmap -q "string" regexp:/etc/postfix/filename
10
11       postmap -q - regexp:/etc/postfix/filename <inputfile
12

DESCRIPTION

14       The  Postfix  mail  system  uses optional tables for address rewriting,
15       mail routing, or access control. These tables are usually in dbm or  db
16       format.
17
18       Alternatively,  lookup tables can be specified in POSIX regular expres‐
19       sion form. In this case, each input is compared against a list of  pat‐
20       terns.  When a match is found, the corresponding result is returned and
21       the search is terminated.
22
23       To find out what types of lookup tables your  Postfix  system  supports
24       use the "postconf -m" command.
25
26       To test lookup tables, use the "postmap -q" command as described in the
27       SYNOPSIS above.
28

COMPATIBILITY

30       With Postfix version 2.2 and earlier specify "postmap -fq" to  query  a
31       table that contains case sensitive patterns. Patterns are case insensi‐
32       tive by default.
33

TABLE FORMAT

35       The general form of a Postfix regular expression table is:
36
37       /pattern/flags result
38              When pattern matches the input  string,  use  the  corresponding
39              result value.
40
41       !/pattern/flags result
42              When  pattern  does  not  match the input string, use the corre‐
43              sponding result value.
44
45       if /pattern/flags
46
47       endif  Match the input string  against  the  patterns  between  if  and
48              endif,  if  and only if that same input string also matches pat‐
49              tern. The if..endif can nest.
50
51              Note: do not prepend whitespace to patterns inside if..endif.
52
53              This feature is available in Postfix 2.1 and later.
54
55       if !/pattern/flags
56
57       endif  Match the input string  against  the  patterns  between  if  and
58              endif, if and only if that same input string does not match pat‐
59              tern. The if..endif can nest.
60
61              Note: do not prepend whitespace to patterns inside if..endif.
62
63              This feature is available in Postfix 2.1 and later.
64
65       blank lines and comments
66              Empty lines and whitespace-only lines are ignored, as are  lines
67              whose first non-whitespace character is a `#'.
68
69       multi-line text
70              A  logical  line  starts  with  non-whitespace text. A line that
71              starts with whitespace continues a logical line.
72
73       Each pattern is a POSIX regular expression enclosed by a pair of delim‐
74       iters. The regular expression syntax is documented in re_format(7) with
75       4.4BSD, in regex(5) with Solaris, and in  regex(7)  with  Linux.  Other
76       systems may use other document names.
77
78       The  expression  delimiter  can  be any character, except whitespace or
79       characters that have special meaning (traditionally the  forward  slash
80       is used). The regular expression can contain whitespace.
81
82       By  default, matching is case-insensitive, and newlines are not treated
83       as special characters. The behavior is controlled by flags,  which  are
84       toggled  by appending one or more of the following characters after the
85       pattern:
86
87       i (default: on)
88              Toggles the case sensitivity flag. By default, matching is  case
89              insensitive.
90
91       m (default: off)
92              Toggle the multi-line mode flag. When this flag is on, the ^ and
93              $ metacharacters match immediately after and immediately  before
94              a  newline  character,  respectively, in addition to matching at
95              the start and end of the input string.
96
97       x (default: on)
98              Toggles the extended expression syntax flag. By default, support
99              for extended expression syntax is enabled.
100

TABLE SEARCH ORDER

102       Patterns  are  applied  in the order as specified in the table, until a
103       pattern is found that matches the input string.
104
105       Each pattern is applied to the entire input string.  Depending  on  the
106       application, that string is an entire client hostname, an entire client
107       IP address, or an entire mail address.  Thus, no parent domain or  par‐
108       ent network search is done, and user@domain mail addresses are not bro‐
109       ken up into their user and domain constituent parts,  nor  is  user+foo
110       broken up into user and foo.
111

TEXT SUBSTITUTION

113       Substitution  of substrings from the matched expression into the result
114       string is possible using $1, $2, etc.; specify $$ to produce a $  char‐
115       acter  as output.  The macros in the result string may need to be writ‐
116       ten as ${n} or $(n) if they aren't followed by whitespace.
117
118       Note: since negated patterns (those preceded by !) return a result when
119       the  expression  does  not  match,  substitutions are not available for
120       negated patterns.
121

EXAMPLE SMTPD ACCESS MAP

123       # Disallow sender-specified routing. This is a must if you relay mail
124       # for other domains.
125       /[%!@].*[%!@]/       550 Sender-specified routing rejected
126
127       # Postmaster is OK, that way they can talk to us about how to fix
128       # their problem.
129       /^postmaster@/       OK
130
131       # Protect your outgoing majordomo exploders
132       if !/^owner-/
133       /^(.*)-outgoing@(.*)$/   550 Use ${1}@${2} instead
134       endif
135

EXAMPLE HEADER FILTER MAP

137       # These were once common in junk mail.
138       /^Subject: make money fast/     REJECT
139       /^To: friend@public\.com/       REJECT
140

EXAMPLE BODY FILTER MAP

142       # First skip over base 64 encoded text to save CPU cycles.
143       ~^[[:alnum:]+/]{60,}$~          OK
144
145       # Put your own body patterns here.
146

SEE ALSO

148       postmap(1), Postfix lookup table manager
149       pcre_table(5), format of PCRE tables
150       cidr_table(5), format of CIDR tables
151

README FILES

153       Use "postconf readme_directory" or "postconf html_directory" to  locate
154       this information.
155       DATABASE_README, Postfix lookup table overview
156

AUTHOR(S)

158       The regexp table lookup code was originally written by:
159       LaMont Jones
160       lamont@hp.com
161
162       That code was based on the PCRE dictionary contributed by:
163       Andrew McNamara
164       andrewm@connect.com.au
165       connect.com.au Pty. Ltd.
166       Level 3, 213 Miller St
167       North Sydney, NSW, Australia
168
169       Adopted and adapted by:
170       Wietse Venema
171       IBM T.J. Watson Research
172       P.O. Box 704
173       Yorktown Heights, NY 10598, USA
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