301 lines
9.9 KiB
Groff
301 lines
9.9 KiB
Groff
.TH PCRE_TABLE 5
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.ad
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.fi
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.SH NAME
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pcre_table
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\-
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format of Postfix PCRE tables
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.SH "SYNOPSIS"
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.na
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.nf
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\fBpostmap \-q "\fIstring\fB" pcre:/etc/postfix/\fIfilename\fR
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\fBpostmap \-q \- pcre:/etc/postfix/\fIfilename\fB <\fIinputfile\fR
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\fBpostmap \-hmq \- pcre:/etc/postfix/\fIfilename\fB <\fIinputfile\fR
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\fBpostmap \-bmq \- pcre:/etc/postfix/\fIfilename\fB <\fIinputfile\fR
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.SH DESCRIPTION
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.ad
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.fi
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The Postfix mail system uses optional tables for address
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rewriting, mail routing, or access control. These tables
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are usually in \fBdbm\fR or \fBdb\fR format.
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Alternatively, lookup tables can be specified in Perl Compatible
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Regular Expression form. In this case, each input is compared
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against a list of patterns. When a match is found, the
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corresponding result is returned and the search is terminated.
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To find out what types of lookup tables your Postfix system
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supports use the "\fBpostconf \-m\fR" command.
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To test lookup tables, use the "\fBpostmap \-q\fR" command
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as described in the SYNOPSIS above. Use "\fBpostmap \-hmq
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\-\fR <\fIfile\fR" for header_checks(5) patterns, and
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"\fBpostmap \-bmq \-\fR <\fIfile\fR" for body_checks(5)
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(Postfix 2.6 and later).
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This driver can be built with the pcre2 library (Postfix
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3.7 and later), or with the legacy pcre library (all Postfix
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versions).
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.SH "COMPATIBILITY"
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.na
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.nf
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.ad
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.fi
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With Postfix version 2.2 and earlier specify "\fBpostmap
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\-fq\fR" to query a table that contains case sensitive
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patterns. Patterns are case insensitive by default.
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.SH "TABLE FORMAT"
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.na
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.nf
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.ad
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.fi
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The general form of a PCRE table is:
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.IP "\fB/\fIpattern\fB/\fIflags result\fR"
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When \fIpattern\fR matches the input string, use
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the corresponding \fIresult\fR value.
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.IP "\fB!/\fIpattern\fB/\fIflags result\fR"
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When \fIpattern\fR does \fBnot\fR match the input string, use
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the corresponding \fIresult\fR value.
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.IP "\fBif /\fIpattern\fB/\fIflags\fR"
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.IP "\fBendif\fR"
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If the input string matches /\fIpattern\fR/, then match that
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input string against the patterns between \fBif\fR and
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\fBendif\fR. The \fBif\fR..\fBendif\fR can nest.
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.sp
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Note: do not prepend whitespace to patterns inside
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\fBif\fR..\fBendif\fR.
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.sp
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This feature is available in Postfix 2.1 and later.
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.IP "\fBif !/\fIpattern\fB/\fIflags\fR"
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.IP "\fBendif\fR"
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If the input string does not match /\fIpattern\fR/, then
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match that input string against the patterns between \fBif\fR
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and \fBendif\fR. The \fBif\fR..\fBendif\fR can nest.
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.sp
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Note: do not prepend whitespace to patterns inside
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\fBif\fR..\fBendif\fR.
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.sp
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This feature is available in Postfix 2.1 and later.
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.IP "blank lines and comments"
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Empty lines and whitespace\-only lines are ignored, as
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are lines whose first non\-whitespace character is a `#'.
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.IP "multi\-line text"
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A logical line starts with non\-whitespace text. A line that
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starts with whitespace continues a logical line.
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.PP
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Each pattern is a perl\-like regular expression. The expression
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delimiter can be any non\-alphanumeric character, except
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whitespace or characters
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that have special meaning (traditionally the forward slash is used).
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The regular expression can contain whitespace.
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By default, matching is case\-insensitive, and newlines are not
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treated as special characters. The behavior is controlled by flags,
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which are toggled by appending one or more of the following
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characters after the pattern:
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.IP "\fBi\fR (default: on)"
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Toggles the case sensitivity flag. By default, matching is case
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insensitive.
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.IP "\fBm\fR (default: off)"
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Toggles the pcre MULTILINE flag. When this flag is on, the \fB^\fR
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and \fB$\fR metacharacters match immediately after and immediately
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before a newline character, respectively, in addition to
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matching at the start and end of the subject string.
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.IP "\fBs\fR (default: on)"
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Toggles the pcre DOTALL flag. When this flag is on, the \fB.\fR
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metacharacter matches the newline character. With
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Postfix versions prior to 2.0, the flag is off by
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default, which is inconvenient for multi\-line message header
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matching.
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.IP "\fBx\fR (default: off)"
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Toggles the pcre extended flag. When this flag is on, whitespace
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characters in the pattern (other than in a character class)
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are ignored. To include a whitespace character as part of
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the pattern, escape it with backslash.
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.sp
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Note: do not use \fB#\fIcomment\fR after patterns.
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.IP "\fBA\fR (default: off)"
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Toggles the pcre ANCHORED flag. When this flag is on,
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the pattern is forced to be "anchored", that is, it is
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constrained to match only at the start of the string which
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is being searched (the "subject string"). This effect can
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also be achieved by appropriate constructs in the pattern
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itself.
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.IP "\fBE\fR (default: off)"
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Toggles the pcre DOLLAR_ENDONLY flag. When this flag is on,
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a \fB$\fR metacharacter in the pattern matches only at the
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end of the subject string. Without this flag, a dollar also
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matches immediately before the final character if it is a
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newline character (but not before any other newline
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characters). This flag is ignored if the pcre MULTILINE
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flag is set.
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.IP "\fBU\fR (default: off)"
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Toggles the pcre UNGREEDY flag. When this flag is on,
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the pattern matching engine inverts the "greediness" of
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the quantifiers so that they are not greedy by default,
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but become greedy if followed by "?". This flag can also
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set by a (?U) modifier within the pattern.
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.IP "\fBX\fR (default: off)"
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Toggles the pcre EXTRA flag.
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When this flag is on, any backslash in a pattern that is
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followed by a letter that has no special meaning causes an
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error, thus reserving these combinations for future expansion.
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This feature is not supported with PCRE2.
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.SH "SEARCH ORDER"
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.na
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.nf
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.ad
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.fi
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Patterns are applied in the order as specified in the table, until a
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pattern is found that matches the input string.
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Each pattern is applied to the entire input string.
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Depending on the application, that string is an entire client
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hostname, an entire client IP address, or an entire mail address.
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Thus, no parent domain or parent network search is done, and
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\fIuser@domain\fR mail addresses are not broken up into their
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\fIuser\fR and \fIdomain\fR constituent parts, nor is \fIuser+foo\fR
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broken up into \fIuser\fR and \fIfoo\fR.
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.SH "TEXT SUBSTITUTION"
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.na
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.nf
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.ad
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.fi
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Substitution of substrings (text that matches patterns
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inside "()") from the matched expression into the result
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string is requested with $1, $2, etc.; specify $$ to produce
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a $ character as output.
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The macros in the result string may need to be written as
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${n} or $(n) if they aren't followed by whitespace.
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This feature does not support pcre2 substring names.
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Note: since negated patterns (those preceded by \fB!\fR) return a
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result when the expression does not match, substitutions are not
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available for negated patterns.
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.SH "INLINE SPECIFICATION"
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.na
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.nf
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.ad
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.fi
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The contents of a table may be specified in the table name
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(Postfix 3.7 and later).
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The basic syntax is:
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.nf
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main.cf:
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\fIparameter\fR \fB= .. pcre:{ { \fIrule\-1\fB }, { \fIrule\-2\fB } .. } ..\fR
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master.cf:
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\fB.. \-o { \fIparameter\fR \fB= .. pcre:{ { \fIrule\-1\fB }, { \fIrule\-2\fB } .. } .. } ..\fR
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.fi
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Postfix recursively expands any \fI$parametername\fR instances
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in the above parameter value, ignores whitespace after '{'
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and before '}', and writes each \fIrule\fR as one text line to
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an in\-memory file:
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.nf
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in\-memory file:
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rule\-1
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rule\-2
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..
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.fi
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Postfix parses the result as if it is a file in /etc/postfix.
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.SH "INLINE SPECIFICATION CAVEATS"
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.na
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.nf
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.ad
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.fi
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.IP \(bu
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When using \fI$parametername\fR inside an inlined pattern,
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use \eQ\fI$parametername\fR\eE to disable metacharacters such as
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\&'.' in the \fI$parametername\fR expansion. Otherwise, the pattern
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may have unexpected matches.
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.IP \(bu
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When an inlined rule must contain \fB$\fR, specify \fB$$\fR
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to keep Postfix from trying to do \fI$name\fR expansion as
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it evaluates a parameter value. To check an inline configuration,
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use the "\fBpostconf \-x\fR" option as shown below:
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.RS
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.IP \(bu
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When a main.cf "\fIparametername = \fI value\fR" setting contains
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an inline pcre: table, use the command "\fBpostconf \-x
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\fIparametername\fR". Verify that there are no "undefined
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parameter" warnings, and that the output has the syntax that
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one would use in a non\-inlined Postfix pcre: file.
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.IP \(bu
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When a master.cf "\fB\-o { \fIparametername = value\fB }\fR"
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override contains an inline pcre: table, use the command
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"\fBpostconf \-Px '*/*/\fIparametername\fB' \fR". Verify that there
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are no "undefined parameter" warnings, and that the output has
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the syntax that one would use in a non\-inlined Postfix pcre: file.
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.RE
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.SH "EXAMPLE SMTPD ACCESS MAP"
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.na
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.nf
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# Protect your outgoing majordomo exploders
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/^(?!owner\-)(.*)\-outgoing@(.*)/ 550 Use ${1}@${2} instead
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# Bounce friend@whatever, except when whatever is our domain (you would
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# be better just bouncing all friend@ mail \- this is just an example).
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/^(friend@(?!my\\.domain$).*)$/ 550 Stick this in your pipe $1
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# A multi\-line entry. The text is sent as one line.
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#
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/^noddy@my\\.domain$/
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\ 550 This user is a funny one. You really don't want to send mail to
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\ them as it only makes their head spin.
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.SH "EXAMPLE HEADER FILTER MAP"
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.na
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.nf
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/^Subject: make money fast/ REJECT
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/^To: friend@public\\.com/ REJECT
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.SH "EXAMPLE BODY FILTER MAP"
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.na
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.nf
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# First skip over base 64 encoded text to save CPU cycles.
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# Requires PCRE version 3.
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~^[[:alnum:]+/]{60,}$~ OK
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# Put your own body patterns here.
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.SH "SEE ALSO"
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.na
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.nf
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postmap(1), Postfix lookup table manager
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postconf(5), configuration parameters
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regexp_table(5), format of POSIX regular expression tables
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.SH "README FILES"
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.na
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.nf
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.ad
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.fi
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Use "\fBpostconf readme_directory\fR" or
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"\fBpostconf html_directory\fR" to locate this information.
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.na
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.nf
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DATABASE_README, Postfix lookup table overview
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.SH "AUTHOR(S)"
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.na
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.nf
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The PCRE table lookup code was originally written by:
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Andrew McNamara
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andrewm@connect.com.au
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connect.com.au Pty. Ltd.
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Level 3, 213 Miller St
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North Sydney, NSW, Australia
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Adopted and adapted by:
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Wietse Venema
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IBM T.J. Watson Research
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P.O. Box 704
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Yorktown Heights, NY 10598, USA
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Wietse Venema
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Google, Inc.
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111 8th Avenue
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New York, NY 10011, USA
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