1MH-ALIAS(5) File Formats Manual MH-ALIAS(5)
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6 mh-alias - format of nmh email-address alias files
7
9 Each line of an nmh alias file takes one of the following forms:
10 alias : address-group
12 alias ; address-group
14 < alias-file
16 ; | : | # comment
18 where:
20 address-group := address-list
22 | < file
23 address-list := address
25 | address-list, address
26 Continuation lines end with “\” followed by a newline character. This
28 also applies to comment lines. Thus, the line following a “\”-termi‐
29 nated comment line is a continuation of that comment line.
30 Alias-file and file are Unix file names. Alias file contents are case-
32 insensitive, with the exception of filesystem path names.
33 If the line starts with a “<”, the file named after the “<” is read for
35 more alias definitions. The reading is done recursively, so a “<” may
36 occur in the beginning of an alias file with the expected results.
37 If the address-group starts with a “<”, the file named after the “<” is
39 read and its contents are added to the address-list for the alias.
40 In match, a trailing “*” on an alias will match just about anything
42 appropriate.
43 An approximation of the way aliases are resolved at posting time is:
45 1) Build a list of all addresses from the message to be delivered,
47 eliminating duplicate addresses.
48 2) For those addresses in the message that have no host specified,
50 perform alias resolution.
51 3) For each line in the alias file, compare “alias” against all of
53 the existing addresses. If a match, remove the matched “alias”
54 from the address list, and add each new address in the address-
55 group to the address list if it is not already on the list. The
56 alias itself is not usually output, rather the address-group
57 that the alias maps to is output instead. If “alias” is termi‐
58 nated with a “;” instead of a “:”, then both the “alias” and the
59 address are output in the correct format (with the alias quoted
60 if necessary and the address wrapped in <>).
61 Since the mh-alias file is read line by line, forward references work,
63 but backward references are not recognized.
64 Example Alias File
66 </etc/nmh/BBoardAliases
67 sgroup: fred, fear, freida
68 fred: frated@UCI.example
69 b-people: Blind List: bill, betty
70 Unix-committee: <unix.aliases
71 news.*: news
72 The first line says that more aliases should immediately be read from
74 the file /etc/nmh/BBoardAliases. Next, “sgroup” is defined as an alias
75 for three names, and one of them, “fred”, is a forward reference to
76 another alias for “frated@UCI.example”.
77 The alias “b-people” is a blind list which includes the addresses
79 “bill” and “betty”; the message will be delivered to those addresses,
80 but the message header will show only “Blind List: ;” (not the
81 addresses). The alias must not be terminated with, or contain, a semi‐
82 colon. Note that blind lists are not supported with the sendmail/pipe
83 mail transport method.
84 The definition of “Unix-committee” is given by reading the file
86 unix.aliases in the user's nmh directory.
87 Lastly, “news.anything” is aliased to “news”; the full stop is just
89 another literal character.
90
92 Aliasfile: Default alias file.
93
95 /etc/nmh/MailAliases
96 System-wide default alias file.
97
99 ali(1), send(1), whom(1), getgrent(3), getpwent(3), post(8)
100
102 Although the forward-referencing semantics of mh-alias files prevent
103 recursion, the alias-file directive may defeat this. Since the number
104 of file descriptors is finite, such infinite recursion will terminate
105 with a meaningless diagnostic when all the fds are used up.
106 Earlier versions of this man page showed a semicolon at the end of the
108 blind list example. That caused the preceding alias to not be
109 expanded. There must not be a semicolon at the end of, or within, the
110 address group of a blind list. post will append the semicolon to the
111 blind list name.
112nmh-1.7.1 2014-04-18 MH-ALIAS(5)