man > mh-alias(5)

MH-ALIAS(5mh)                                                                          MH-ALIAS(5mh)

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

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

            alias : address-group

            alias ; address-group

            < alias-file

            ; | : | # comment

       where:

            address-group  := address-list
                           |  < file

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

       Continuation  lines  end with “\” followed by a newline character.  This also applies to com‐
       ment lines.  Thus, the line following a “\”-terminated 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 defini‐
       tions.  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 appropriate.

       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 resolu‐
              tion.

       3)     For each line in the alias file, compare “alias”  against  all  of  the  existing  ad‐
              dresses.   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 terminated 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 refer‐
       ences are not recognized.

   Example Alias File
            </etc/nmh/BBoardAliases
            sgroup: fred, fear, freida
            fred: frated AT 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
       /etc/nmh/BBoardAliases.   Next,  “sgroup”  is defined as an alias for three names, and one of
       them, “fred”, is a forward reference to another alias for “frated AT 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 addresses).  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 another  literal  charac‐
       ter.

PROFILE COMPONENTS
       Aliasfile:          Default alias file.

FILES
       /etc/nmh/MailAliases
                           System-wide default alias file.

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

BUGS
       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  infi‐
       nite 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 expanded.  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-1.8                                      2014-04-18                                MH-ALIAS(5mh)