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MH-ALIAS(5)		      File Formats Manual		   MH-ALIAS(5)

       mh-alias	- format of nmh	email-address alias files

       Each line of an nmh alias file takes one	of the following forms:

	    alias : address-group

	    alias ; address-group

	    < alias-file

	    ; |	: | # comment


	    address-group  := address-list
			   |  <	file

	    address-list   := address
			   |  address-list, address

       Continuation  lines end with "\"	followed by a newline character.  This
       also applies to comment lines.  Thus, the line following	 a  "\"-termi-
       nated comment line is a continuation of that comment line.

       Alias-file and file are Unix file names.	 Alias file contents are case-
       insensitive, with the exception of filesystem path names.

       If the line starts with a "<", the file named after the "<" is read for
       more  alias definitions.	 The reading is	done recursively, so a "<" may
       occur in	the beginning of an alias file with the	expected results.

       If the address-group starts with	a "<", the file	named after the	"<" is
       read and	its contents are added to the address-list for the alias.

       In match, a trailing "*"	on an alias will match just about anything ap-

       An approximation	of the way aliases are resolved	at posting time	is:

       1)     Build a list of all addresses from the message to	be  delivered,
	      eliminating duplicate addresses.

       2)     For  those addresses in the message that have no host specified,
	      perform alias resolution.

       3)     For each line in the alias file, compare "alias" against all  of
	      the  existing addresses.	If a match, remove the matched "alias"
	      from the address list, and add each new address in the  address-
	      group to the address list	if it is not already on	the list.  The
	      alias itself is not usually  output,  rather  the	 address-group
	      that  the	alias maps to is output	instead.  If "alias" is	termi-
	      nated with a ";" instead of a ":", then both the "alias" and the
	      address  are output in the correct format	(with the alias	quoted
	      if necessary and the address wrapped in <>).

       Since the mh-alias file is read line by line, forward references	 work,
       but backward references are not recognized.

   Example Alias File
	    sgroup: fred, fear,	freida
	    fred: frated@UCI.example
	    b-people: Blind List: bill,	betty
	    Unix-committee: <unix.aliases
	    news.*: news

       The  first  line	says that more aliases should immediately be read from
       the file	/usr/local/etc/nmh/BBoardAliases.  Next, "sgroup"  is  defined
       as an alias for three names, and	one of them, "fred", is	a forward ref-
       erence to another alias for "frated@UCI.example".

       The alias "b-people" is a  blind	 list  which  includes	the  addresses
       "bill"  and  "betty"; the message will be delivered to those addresses,
       but the message header will show	only "Blind  List:  ;"	(not  the  ad-
       dresses).   The	alias must not be terminated with, or contain, a semi-
       colon.  Note that blind lists are not supported with the	 sendmail/pipe
       mail transport method.

       The  definition	of  "Unix-committee"  is  given	 by  reading  the file
       unix.aliases in the user's nmh directory.

       Lastly, "news.anything" is aliased to "news"; the full stop is just an-
       other literal character.

       Aliasfile:	   Default alias file.

			   System-wide default alias file.

       ali(1), send(1),	whom(1), getgrent(3), getpwent(3), post(8)

       Although	 the  forward-referencing  semantics of	mh-alias files prevent
       recursion, the alias-file directive may defeat this.  Since the	number
       of  file	 descriptors is	finite,	such infinite recursion	will terminate
       with a meaningless diagnostic when all the fds are used up.

       Earlier versions	of this	man page showed	a semicolon at the end of  the
       blind  list  example.   That  caused  the preceding alias to not	be ex-
       panded.	There must not be a semicolon at the end of,  or  within,  the
       address	group  of a blind list.	 post will append the semicolon	to the
       blind list name.

nmh-1.7.1			  2014-04-18			   MH-ALIAS(5)


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