Provided by: nmh_1.5-release-5_amd64 
NAME
mh-alias - alias file for nmh message system
SYNOPSIS
any nmh command
DESCRIPTION
This describes both nmh personal alias files and the global alias file for nmh mail
delivery, the file
/etc/nmh/MailAliases
It does not describe aliases files used by the message transport system. Each line of the
alias file has the format:
alias : address-group
or
alias ; address-group
or
< alias-file
or
; comment
where:
address-group := address-list
| < file
| = UNIX-group
| + UNIX-group
| *
address-list := address
| address-list, address
Continuation lines in alias files end with `\' followed by the newline character.
“Alias-file” and “file” are UNIX file names. UNIX-group is a group name (or number) from
/etc/group. An address is a “simple” Internet-style address. Througout this file, case
is ignored, except for file names.
If the line starts with a `<', then 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 `<', then the file named after the `<' is read and its
contents are added to the address-list for the alias.
If the address-group starts with an `=', then the file /etc/group is consulted for the
UNIX-group named after the `='. Each login name occurring as a member of the group is
added to the address-list for the alias.
In contrast, if the address-group starts with a `+', then the file /etc/group is consulted
to determine the group-id of the UNIX-group named after the `+'. Each login name
occurring in the /etc/passwd file whose group-id is indicated by this group is added to
the address-list for the alias.
If the address-group is simply `*', then the file /etc/passwd is consulted and all login
names with a userid greater than some magic number (usually 200) are added to the
address-list for the alias.
In match, a trailing “*” on an alias will match just about anything appropriate. (See
example below.)
An approximation of the way aliases are resolved at posting time is (it's not really done
this way):
1) Build a list of all addresses from the message to be delivered, eliminating duplicate
addresses.
2) If this draft originated on the local host, then 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 terminated with a `;' instead of a
`:', then both the “alias” and the address are output in the correct format. (This
makes replies possible since nmh aliases and personal aliases are unknown to the mail
transport system.)
Since the alias file is read line by line, forward references work, but backward
references are not recognized, thus, there is no recursion.
Example Alias File:
</etc/nmh/BBoardAliases
sgroup: fred, fear, freida
b-people: Blind List: bill, betty;
fred: frated@UCI
UNIX-committee: <unix.aliases
staff: =staff
wheels: +wheel
everyone: *
news.*: news
The first line says that more aliases should immediately be read from the file
/etc/nmh/BBoardAliases. Following this, “fred” is defined as an alias for “frated@UCI”,
and “sgroup” is defined as an alias for the three names “frated@UCI”, ”fear”, and
”freida”.
The alias “b-people” is a blind list which includes the addresses “bill” and “betty”; the
message will be delieved to those addresses, but the message header will show only “Blind
List: ;” (not the addresses).
Next, the definition of “UNIX-committee” is given by reading the file unix.aliases in the
users nmh directory, “staff” is defined as all users who are listed as members of the
group “staff” in the /etc/group file, and “wheels” is defined as all users whose group-id
in /etc/passwd is equivalent to the “wheel” group.
Finally, “everyone” is defined as all users with a user-id in /etc/passwd greater than
200, and all aliases of the form “news.<anything>” are defined to be “news”.
The key thing to understand about aliasing in nmh is that aliases in nmh alias files are
expanded into the headers of messages posted. This aliasing occurs first, at posting
time, without the knowledge of the message transport system. In contrast, once the
message transport system is given a message to deliver to a list of addresses, for each
address that appears to be local, a system-wide alias file is consulted. These aliases
are NOT expanded into the headers of messages delivered.
HELPFUL HINTS
To use aliasing in nmh quickly, do the following:
1) In your .mh_profile, choose a name for your alias file, say “aliases”, and add the
line:
Aliasfile: aliases
2) Create the file “aliases” in your nmh directory.
3) Start adding aliases to your “aliases” file as appropriate.
FILES
/etc/nmh/MailAliases global nmh alias file
PROFILE COMPONENTS
Aliasfile: For a default alias file
SEE ALSO
ali(1), send(1), whom(1), group(5), passwd(5), conflict(8), post(8)
CONTEXT
None
BUGS
Although the forward-referencing semantics of mh-alias files prevent recursion, the “<
alias-file” command may defeat this. Since the number of file descriptors is finite (and
very limited), such infinite recursion will terminate with a meaningless diagnostic when
all the fds are used up.
Forward references do not work correctly inside blind lists.