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PCRE_TABLE(5) PCRE_TABLE(5)
<b>NAME</b>
pcre_table - format of Postfix PCRE tables
<b>SYNOPSIS</b>
<b>postmap -q "</b><i>string</i><b>" <a href="pcre_table.5.html">pcre</a>:/etc/postfix/</b><i>filename</i>
<b>postmap -q - <a href="pcre_table.5.html">pcre</a>:/etc/postfix/</b><i>filename</i> <<i>inputfile</i>
<b>postmap -hmq - <a href="pcre_table.5.html">pcre</a>:/etc/postfix/</b><i>filename</i> <<i>inputfile</i>
<b>postmap -bmq - <a href="pcre_table.5.html">pcre</a>:/etc/postfix/</b><i>filename</i> <<i>inputfile</i>
<b>DESCRIPTION</b>
The Postfix mail system uses optional tables for address rewriting,
mail routing, or access control. These tables are usually in <b>dbm</b> or <b>db</b>
format.
Alternatively, lookup tables can be specified in Perl Compatible Regu-
lar 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 "<b>postconf -m</b>" command.
To test lookup tables, use the "<b>postmap -q</b>" command as described in the
SYNOPSIS above. Use "<b>postmap -hmq -</b> <<i>file</i>" for <a href="header_checks.5.html">header_checks(5)</a> pat-
terns, and "<b>postmap -bmq -</b> <<i>file</i>" for <a href="header_checks.5.html">body_checks(5)</a> (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).
<b>COMPATIBILITY</b>
With Postfix version 2.2 and earlier specify "<b>postmap -fq</b>" to query a
table that contains case sensitive patterns. Patterns are case insensi-
tive by default.
<b>TABLE FORMAT</b>
The general form of a PCRE table is:
<b>/</b><i>pattern</i><b>/</b><i>flags result</i>
When <i>pattern</i> matches the input string, use the corresponding
<i>result</i> value.
<b>!/</b><i>pattern</i><b>/</b><i>flags result</i>
When <i>pattern</i> does <b>not</b> match the input string, use the corre-
sponding <i>result</i> value.
<b>if /</b><i>pattern</i><b>/</b><i>flags</i>
<b>endif</b> If the input string matches /<i>pattern</i>/, then match that input
string against the patterns between <b>if</b> and <b>endif</b>. The <b>if</b>..<b>endif</b>
can nest.
Note: do not prepend whitespace to patterns inside <b>if</b>..<b>endif</b>.
This feature is available in Postfix 2.1 and later.
<b>if !/</b><i>pattern</i><b>/</b><i>flags</i>
<b>endif</b> If the input string does not match /<i>pattern</i>/, then match that
input string against the patterns between <b>if</b> and <b>endif</b>. The
<b>if</b>..<b>endif</b> can nest.
Note: do not prepend whitespace to patterns inside <b>if</b>..<b>endif</b>.
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 delim-
iter can be any non-alphanumeric character, except whitespace or char-
acters 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:
<b>i</b> (default: on)
Toggles the case sensitivity flag. By default, matching is case
insensitive.
<b>m</b> (default: off)
Toggles the pcre MULTILINE flag. When this flag is on, the <b>^</b> and
<b>$</b> metacharacters match immediately after and immediately before
a newline character, respectively, in addition to matching at
the start and end of the subject string.
<b>s</b> (default: on)
Toggles the pcre DOTALL flag. When this flag is on, the <b>.</b>
metacharacter matches the newline character. With Postfix ver-
sions prior to 2.0, the flag is off by default, which is incon-
venient for multi-line message header matching.
<b>x</b> (default: off)
Toggles the pcre extended flag. When this flag is on, whitespace
characters in the pattern (other than in a character class) are
ignored. To include a whitespace character as part of the pat-
tern, escape it with backslash.
Note: do not use <b>#</b><i>comment</i> after patterns.
<b>A</b> (default: off)
Toggles the pcre ANCHORED flag. When this flag is on, the pat-
tern is forced to be "anchored", that is, it is constrained to
match only at the start of the string which is being searched
(the "subject string"). This effect can also be achieved by
appropriate constructs in the pattern itself.
<b>E</b> (default: off)
Toggles the pcre DOLLAR_ENDONLY flag. When this flag is on, a <b>$</b>
metacharacter in the pattern matches only at the end of the sub-
ject 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 characters). This flag is
ignored if the pcre MULTILINE flag is set.
<b>U</b> (default: off)
Toggles the pcre UNGREEDY flag. When this flag is on, the pat-
tern 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.
<b>X</b> (default: off)
Toggles the pcre EXTRA flag. When this flag is on, any back-
slash in a pattern that is followed by a letter that has no spe-
cial meaning causes an error, thus reserving these combinations
for future expansion.
This feature is not supported with PCRE2.
<b>SEARCH ORDER</b>
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 par-
ent network search is done, and <i>user@domain</i> mail addresses are not bro-
ken up into their <i>user</i> and <i>domain</i> constituent parts, nor is <i>user+foo</i>
broken up into <i>user</i> and <i>foo</i>.
<b>TEXT SUBSTITUTION</b>
Substitution of substrings (text that matches patterns inside "()")
from the matched expression into the result string is requested with
$1, $2, etc.; specify $$ to produce a $ character as output. The
macros in the result string may need to be written as ${n} or $(n) if
they aren't followed by whitespace. This feature does not support
pcre2 substring names.
Note: since negated patterns (those preceded by <b>!</b>) return a result when
the expression does not match, substitutions are not available for
negated patterns.
<b>INLINE SPECIFICATION</b>
The contents of a table may be specified in the table name. The basic
syntax is:
<a href="postconf.5.html">main.cf</a>:
<i>parameter</i> <b>= .. <a href="pcre_table.5.html">pcre</a>:{ {</b> <i>rule-1</i> <b>}, {</b> <i>rule-2</i> <b>} .. } ..</b>
<a href="master.5.html">master.cf</a>:
<b>.. -o {</b> <i>parameter</i> <b>= .. <a href="pcre_table.5.html">pcre</a>:{ {</b> <i>rule-1</i> <b>}, {</b> <i>rule-2</i> <b>} .. } .. } ..</b>
Postfix ignores whitespace after '{' and before '}', and writes each
<i>rule</i> as one text line to an in-memory file:
in-memory file:
rule-1
rule-2
..
Postfix parses the result as if it is a file in /etc/postfix.
Note: if a rule contains <b>$</b>, specify <b>$$</b> to keep Postfix from trying to
do <i>$name</i> expansion as it evaluates a parameter value.
<b>EXAMPLE SMTPD ACCESS MAP</b>
# 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.
<b>EXAMPLE HEADER FILTER MAP</b>
/^Subject: make money fast/ REJECT
/^To: friend@public\.com/ REJECT
<b>EXAMPLE BODY FILTER MAP</b>
# First skip over base 64 encoded text to save CPU cycles.
# Requires PCRE version 3.
~^[[:alnum:]+/]{60,}$~ OK
# Put your own body patterns here.
<b>SEE ALSO</b>
<a href="postmap.1.html">postmap(1)</a>, Postfix lookup table manager
<a href="postconf.5.html">postconf(5)</a>, configuration parameters
<a href="regexp_table.5.html">regexp_table(5)</a>, format of POSIX regular expression tables
<b>README FILES</b>
<a href="DATABASE_README.html">DATABASE_README</a>, Postfix lookup table overview
<b>AUTHOR(S)</b>
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)
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