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1.1 root 1: .\" @(MHWARNING)
2: .TH MH\-ALIAS 5 "April 22, 1986" MH [mh.6]
3: .UC 6
4: .SH NAME
5: mh\-alias \- alias file for MH message system
6: .SH SYNOPSIS
7: .in +.5i
8: .ti -.5i
9: any \fIMH\fR command
10: .in -.5i
11: .SH DESCRIPTION
12: This describes both \fIMH\fR personal alias files and
13: the (primary) alias file for mail delivery, the file
14:
15: @(MHETCPATH)/MailAliases
16:
17: It does \fBnot\fR describe aliases files used by the message transport system.
18: Each line of the alias file has the format:
19:
20: alias : address\-group
21: .br
22: or
23: .br
24: alias ; address\-group
25: .br
26: or
27: .br
28: < alias\-file
29: .br
30:
31: where:
32:
33: address\-group := address\-list
34: .br
35: | \*(lq<\*(rq file
36: .br
37: | \*(lq=\*(rq UNIX\-group
38: .br
39: | \*(lq+\*(rq UNIX\-group
40: .br
41: | \*(lq*\*(rq
42:
43: .br
44: address\-list := address
45: .br
46: | address\-list, address
47: .br
48:
49: Continuation lines in alias files end with `\\' followed by the newline
50: character.
51:
52: Alias\-file and file are UNIX file names.
53: UNIX\-group is a group name (or number) from \fI/etc/group\fR.
54: An address is a \*(lqsimple\*(rq Internet\-style address.
55: Througout this file, case is ignored, except for alias\-file names.
56:
57: If the line starts with a `<', then the file named after the `<' is
58: read for more alias definitions. The reading is done recursively, so a `<'
59: may occur in the beginning of an alias file with the expected results.
60:
61: If the address\-group starts with a `<',
62: then the file named after the `<' is read and its contents are added to
63: the address\-list for the alias.
64:
65: If the address\-group starts with an `=',
66: then the file \fI/etc/group\fR is consulted
67: for the UNIX\-group named after the `='.
68: Each login name occurring as a member of the group is added to the
69: address\-list for the alias.
70:
71: In contrast, if the address\-group starts with a `+',
72: then the file \fI/etc/group\fR is consulted
73: to determine the group\-id of the UNIX\-group named after the `+'.
74: Each login name occurring in the \fI/etc/passwd\fR file whose group\-id
75: is indicated by this group is added to the address\-list for the alias.
76:
77: If the address\-group is simply `*',
78: then the file \fI/etc/passwd\fR is consulted
79: and all login names with a userid greater than some magic number
80: (usually 200) are added to the address\-list for the alias.
81:
82: In match, a trailing * on an alias will match just about anything appropriate.
83: (See example below.)
84:
85: An approximation of the way aliases are resolved at posting time is
86: (it's not really done this way):
87:
88: .in +.5i
89: 1) Build a list of all addresses from the message to be
90: delivered, eliminating duplicate addresses.
91:
92: 2) If this draft originated on the local host,
93: then for those addresses in the message that have no host specified,
94: perform alias resolution.
95:
96: 3) For each line in the alias file,
97: compare \*(lqalias\*(rq against all of the existing addresses.
98: If a match, remove the matched \*(lqalias\*(rq from the address list,
99: and add each new address in the address\-group to the address list
100: if it is not already on the list.
101: The alias itself is not usually output,
102: rather the address\-group that the alias maps to is output instead.
103: If \*(lqalias\*(rq is terminated with a `;' instead of a `:',
104: then both the \*(lqalias\*(rq and the address are output
105: in the correct format.
106: (This makes replies possible since \fIMH\fR aliases and
107: personal aliases are unknown to the mail transport system.)
108: .in -.5i
109:
110: Since the alias file is read line by line, forward references
111: work, but backward references are not recognized, thus, there is
112: no recursion.
113:
114: \fBExample:\fR
115: .nf
116: .in +.5i
117: <@(MHETCPATH)/BBoardAliases
118: sgroup: fred, fear, freida
119: fred: frated@UCI
120: UNIX\-committee: <unix.aliases
121: staff: =staff
122: wheels: +wheel
123: everyone: *
124: news.*: news
125: .in -.5i
126: .fi
127:
128: The first line says that more aliases should immediately be read from
129: the file \fI@(MHETCPATH)/BBoardAliases\fR.
130: Following this, \*(lqfred\*(rq is defined as an alias for
131: \*(lqfrated@UCI\*(rq,
132: and \*(lqsgroup\*(rq is defined as an alias for
133: the three names \*(lqfrated@UCI\*(rq, \*(rqfear\*(rq, and \*(rqfreida\*(rq.
134: Next, the definition of \*(lqUNIX\-committee\*(rq is given by reading
135: the file \fIunix.aliases\fR in the users \fIMH\fR directory,
136: \*(lqstaff\*(rq is defined as all users who are listed as members of
137: the group \*(lqstaff\*(rq in the \fI/etc/group\fR file,
138: and \*(lqwheels\*(rq is defined as all users whose group\-id in
139: \fI/etc/passwd\fR is equivalent to the \*(lqwheel\*(rq group.
140: Finally, \*(lqeveryone\*(rq is defined as all users with a user\-id in
141: \fI/etc/passwd\fR greater than 200,
142: and all aliases of the form \*(lqnews.<anything>\*(rq are defined
143: to be \*(lqnews\*(rq.
144:
145: The key thing to understand about aliasing in \fIMH\fR
146: is that aliases in \fIMH\fR alias files are expanded into the
147: headers of messages posted.
148: This aliasing occurs first,
149: at posting time,
150: without the knowledge of the message transport system.
151: In contrast,
152: once the message transport system is given a message to deliver
153: to a list of addresses,
154: for each address that appears to be local,
155: a system\-wide alias file is consulted.
156: These aliases are \fBNOT\fR expanded into the headers of messages delivered.
157: .Hh
158: To use aliasing in \fIMH\fR quickly, do the following:
159:
160: .in +.5i
161: First, in your \fI\&.mh\(ruprofile\fR,
162: choose a name for your primary alias file, say \*(lqaliases\*(rq,
163: and add three lines:
164:
165: .nf
166: .in +.5i
167: ali: \-alias aliases
168: send: \-alias aliases
169: whom: \-alias ailases
170: .in -.5i
171: .fi
172:
173: Second, create the file \*(lqaliases\*(rq in your \fIMH\fR directory.
174:
175: Third, start adding aliases to your \*(lqaliases\*(rq file as appropriate.
176: .in -.5i
177: .Fi
178: ^@(MHETCPATH)/MailAliases~^Primary alias file
179: .Pr
180: None
181: .Sa
182: ali(1), send(1), whom(1), group(5), passwd(5), conflict(8), post(8)
183: .De
184: None
185: .Co
186: None
187: .Hi
188: In previous releases of \fIMH\fR,
189: only a single, system\-wide mh\-alias file was supported.
190: @BEGIN: MMDFMTS
191: Now that \fIMH\fR uses \fIMMDF\fR as a transport system,
192: the system\-wide aliasing facility can be more consistently controlled by the
193: latter.
194: This means that at most sites,
195: the system\-wide mh\-alias file will be empty (or trivial at best).
196: @END: MMDFMTS
197: @BEGIN: MHMTS
198: This led to a number of problems,
199: since only mail\-system administrators were capable of (un)defining
200: aliases.
201: @END: MHMTS
202: @BEGIN: SENDMTS
203: This led to a number of problems,
204: since only mail\-system administrators were capable of (un)defining
205: aliases.
206: @END: SENDMTS
207: Hence,
208: the semantics of mh\-alias were extended to support personal alias files.
209: Users of \fIMH\fR no longer need to bother mail\-system administrators for
210: keeping information in the system\-wide alias file,
211: as each \fIMH\fR user can create/modify/remove aliases at will from any
212: number of personal files.
213: .Bu
214: Although the forward\-referencing semantics of \fImh\-alias\fR files prevent
215: recursion, the \*(lq<\ alias\-file\*(rq command may defeat this. Since the
216: number of file descriptors is finite (and very limited), such infinite
217: recursion will terminate with a meaningless diagnostic when all the fds are
218: used up.
219: .En
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