#++
# NAME
#	regexp_table 5
# SUMMARY
#	format of Postfix regular expression tables
# SYNOPSIS
#	\fBpostmap -q "\fIstring\fB" regexp:/etc/postfix/\fIfilename\fR
#
#	\fBpostmap -q - regexp:/etc/postfix/\fIfilename\fR <\fIinputfile\fR
# DESCRIPTION
#	The Postfix mail system uses optional tables for address
#	rewriting, mail routing, or access control. These tables
#	are usually in \fBdbm\fR or \fBdb\fR format.
#
#	Alternatively, lookup tables can be specified in POSIX 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 "\fBpostconf -m\fR" command.
#
#	To test lookup tables, use the "\fBpostmap -q\fR" command
#	as described in the SYNOPSIS above.
# COMPATIBILITY
# .ad
# .fi
#	With Postfix version 2.2 and earlier specify "\fBpostmap
#	-fq\fR" to query a table that contains case sensitive
#	patterns. Patterns are case insensitive by default.
# TABLE FORMAT
# .ad
# .fi
#	The general form of a Postfix regular expression table is:
# .IP "\fB/\fIpattern\fB/\fIflags result\fR"
#	When \fIpattern\fR matches the input string,
#	use the corresponding \fIresult\fR value.
# .IP "\fB!/\fIpattern\fB/\fIflags result\fR"
#	When \fIpattern\fR does \fBnot\fR match the input string,
#	use the corresponding \fIresult\fR value.
# .IP "\fBif /\fIpattern\fB/\fIflags\fR"
# .IP "\fBendif\fR"
#       Match the input string against the patterns between \fBif\fR
#	and \fBendif\fR, if and only if that same input string also
#	matches \fIpattern\fR. The \fBif\fR..\fBendif\fR can nest.
# .sp
#       Note: do not prepend whitespace to patterns inside
#	\fBif\fR..\fBendif\fR.
# .sp
#	This feature is available in Postfix 2.1 and later.
# .IP "\fBif !/\fIpattern\fB/\fIflags\fR"
# .IP "\fBendif\fR"
#       Match the input string against the patterns between \fBif\fR
#	and \fBendif\fR, if and only if that same input string does
#	\fBnot\fR match \fIpattern\fR. The \fBif\fR..\fBendif\fR can nest.
# .sp
#       Note: do not prepend whitespace to patterns inside
#	\fBif\fR..\fBendif\fR.
# .sp
#	This feature is available in Postfix 2.1 and later.
# .IP "blank lines and comments"
#	Empty lines and whitespace-only lines are ignored, as
#	are lines whose first non-whitespace character is a `#'.
# .IP "multi-line text"
#	A logical line starts with non-whitespace text. A line that
#	starts with whitespace continues a logical line.
# .PP
#	Each pattern is a POSIX regular expression enclosed by a pair of
#	delimiters. The regular expression syntax is documented in
#	\fBre_format\fR(7) with 4.4BSD, in \fBregex\fR(5) with Solaris, and in
#	\fBregex\fR(7) with Linux. Other systems may use other document names.
#
#	The expression delimiter can be any 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:
# .IP "\fBi\fR (default: on)"
#	Toggles the case sensitivity flag. By default, matching is case
#	insensitive.
# .IP "\fBm\fR (default: off)"
#	Toggle the multi-line mode flag. When this flag is on, the \fB^\fR
#	and \fB$\fR metacharacters match immediately after and immediately
#	before a newline character, respectively, in addition to
#	matching at the start and end of the input string.
# .IP "\fBx\fR (default: on)"
#	Toggles the extended expression syntax flag. By default, support
#	for extended expression syntax is enabled.
# TABLE SEARCH ORDER
# .ad
# .fi
#	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
#	\fIuser@domain\fR mail addresses are not broken up into their
#	\fIuser\fR and \fIdomain\fR constituent parts, nor is \fIuser+foo\fR
#	broken up into \fIuser\fR and \fIfoo\fR.
# TEXT SUBSTITUTION
# .ad
# .fi
#	Substitution of substrings from the matched expression into the result
#	string is possible using $1, $2, etc.;
#	specify $$ to produce a $ character as output.
#	The macros in the result string
#	may need to be written as ${n} or $(n) if they aren't followed
#	by whitespace.
#
#	Note: since negated patterns (those preceded by \fB!\fR) return a
#	result when the expression does not match, substitutions are not
#	available for negated patterns.
# EXAMPLE SMTPD ACCESS MAP
#	# Disallow sender-specified routing. This is a must if you relay mail
#	# for other domains.
#	/[%!@].*[%!@]/	     550 Sender-specified routing rejected
#
#	# Postmaster is OK, that way they can talk to us about how to fix
#	# their problem.
#	/^postmaster@/	     OK
#
#	# Protect your outgoing majordomo exploders
#	if !/^owner-/
#	/^(.*)-outgoing@(.*)$/	 550 Use ${1}@${2} instead
#	endif
# EXAMPLE HEADER FILTER MAP
#	# These were once common in junk mail.
#	/^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.
#	~^[[:alnum:]+/]{60,}$~		OK
#
#	# Put your own body patterns here.
# SEE ALSO
#	postmap(1), Postfix lookup table manager
#	pcre_table(5), format of PCRE tables
#	cidr_table(5), format of CIDR tables
# README FILES
# .ad
# .fi
#	Use "\fBpostconf readme_directory\fR" or
#	"\fBpostconf html_directory\fR" to locate this information.
# .na
# .nf
#	DATABASE_README, Postfix lookup table overview
# AUTHOR(S)
#	The regexp table lookup code was originally written by:
#	LaMont Jones
#	lamont@hp.com
#
#	That code was based on the PCRE dictionary contributed 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
#--