diplodocus.org Git - nmh/blob - man/mh-alias.man

   1 .TH MH-ALIAS %manext5% "Oct 14, 2012" "%nmhversion%"
   2 .\"
   3 .\" %nmhwarning%
   4 .\"
   5 .SH NAME
   6 mh-alias \- format of nmh alias files
   7 .SH DESCRIPTION
   8 .PP
   9 Each line of an
  10 .B nmh
  11 alias file takes one of the following forms:
  12 .PP
  13 .RS 5
  14 .I alias
  15 .B :
  16 .I address\-group
  17 .RE
  18 .sp
  19 .RS 5
  20 .I alias
  21 .B ;
  22 .I address\-group
  23 .RE
  24 .sp
  25 .RS 5
  26 .B <
  27 .I alias\-file
  28 .RE
  29 .sp
  30 .RS 5
  31 .B ;
  32 |
  33 .B :
  34 |
  35 .B #
  36 .I comment
  37 .RE
  38 .PP
  39 where:
  40 .PP
  41 .RS 5
  42 .nf
  43 .IR address\-group "    := " address\-list
  44 .RI "                   |  < " file
  45 .RI "                   |  = " UNIX\-group
  46 .RI "                   |  + " UNIX\-group
  47                         |  *
  48
  49 .IR address\-list "     := " address
  50 .RI "                   |  " address\-list ", " address
  51 .fi
  52 .RE
  53 .PP
  54 Continuation lines end with \*(lq\\\*(rq followed by a newline
  55 character.  This also applies to comment lines.  Thus, the line following a
  56 \*(lq\\\*(rq\-terminated
  57 comment line is a continuation of
  58 that comment line.
  59 .PP
  60 .I Alias\-file
  61 and
  62 .I file
  63 are UNIX file names.
  64 .I UNIX\-group
  65 is a group name or number from
  66 the system's group database.
  67 Alias file contents are case-insensitive, with the exception
  68 of filesystem path names.
  69 .PP
  70 If the line starts with a \*(lq<\*(rq, the file named after the \*(lq<\*(rq is
  71 read for more alias definitions.  The reading is done recursively, so a
  72 \*(lq<\*(rq may occur in the beginning of an alias file with the expected results.
  73 .PP
  74 If the
  75 .I address\-group
  76 starts with a \*(lq<\*(rq, the file named after the
  77 \*(lq<\*(rq is read and its contents are added to the
  78 .I address\-list
  79 for the alias.
  80 .PP
  81 If the
  82 .I address\-group
  83 starts with an \*(lq=\*(rq, the
  84 system's group database
  85 is consulted for the UNIX\-group named after the \*(lq=\*(rq.  Each login name
  86 occurring as a member of the group is added to the
  87 .I address\-list
  88 for the alias.
  89 .PP
  90 In contrast, if the
  91 .I address\-group
  92 starts with a \*(lq+\*(rq, the system's group database
  93 is consulted to determine the group\-id of the
  94 UNIX\-group named after the \*(lq+\*(rq.  Each login name occurring in the
  95 system's password database
  96 whose group\-id is indicated by this group is
  97 added to the
  98 .I address\-list
  99 for the alias.
 100 .PP
 101 If the
 102 .I address\-group
 103 is simply \*(lq*\*(rq, the system's password database
 104 is consulted and all login names with a userid
 105 greater than some magic number (usually 200) are added to the
 106 .I address\-list
 107 for the alias.
 108 .B
 109 This feature is obsolescent and will be removed in a future release.
 110 .PP
 111 In match, a trailing \*(lq*\*(rq on an alias will match just about anything
 112 appropriate.
 113 .PP
 114 An approximation of the way aliases are resolved at posting time is:
 115 .IP 1)
 116 Build a list of all addresses from the message to be delivered,
 117 eliminating duplicate addresses.
 118 .IP 2)
 119 If this draft originated on the local host, then for those addresses in
 120 the message that have no host specified, perform alias resolution.
 121 .IP 3)
 122 For each line in the alias file, compare \*(lqalias\*(rq against all of
 123 the existing addresses.  If a match, remove the matched \*(lqalias\*(rq
 124 from the address list, and add each new address in the address\-group to
 125 the address list if it is not already on the list.  The alias itself is
 126 not usually output, rather the address\-group that the alias maps to is
 127 output instead.  If \*(lqalias\*(rq is terminated with a \*(lq;\*(rq instead of
 128 a \*(lq:\*(rq, then both the \*(lqalias\*(rq and the address are output in the
 129 correct format (with the alias quoted if necessary and the address
 130 wrapped in <>).
 131 .PP
 132 Since the
 133 .I mh-alias
 134 file is read line by line, forward references work, but
 135 backward references are not recognized.
 136 .SS
 137 Example Alias File
 138 .PP
 139 .RS 5
 140 .nf
 141 <%etcdir%/BBoardAliases
 142 fred: frated@UCI.example
 143 sgroup: fred, fear, freida
 144 b-people: Blind List: bill, betty
 145 UNIX\-committee: <unix.aliases
 146 staff: =staff
 147 wheels: +wheel
 148 news.*: news
 149 .fi
 150 .RE
 151 .PP
 152 The first line says that more aliases should immediately be read from
 153 the file
 154 .BR %etcdir%/BBoardAliases .
 155 Following this, \*(lqfred\*(rq
 156 is defined as an alias for \*(lqfrated@UCI.example\*(rq, and \*(lqsgroup\*(rq
 157 is defined as an alias for the three names \*(lqfrated@UCI.example\*(rq,
 158 \*(rqfear\*(rq, and \*(rqfreida\*(rq.
 159 .PP
 160 The alias \*(lqb-people\*(rq is a blind list which includes the addresses
 161 \*(lqbill\*(rq and \*(lqbetty\*(rq; the message will be delivered to those
 162 addresses, but the message header will show only \*(lqBlind List: ;\*(rq
 163 (not the addresses).  The alias must not be terminated with, or contain,
 164 a semicolon.
 165 Note that blind lists are not supported with the
 166 .B sendmail/pipe
 167 mail transport method.
 168 .PP
 169 Next, the definition of \*(lqUNIX\-committee\*(rq is given by
 170 reading the file
 171 .I unix.aliases
 172 in the user's
 173 .B nmh
 174 directory,
 175 \*(lqstaff\*(rq is defined as all users who are listed as members of the
 176 group \*(lqstaff\*(rq in the
 177 system's group database, and \*(lqwheels\*(rq
 178 is defined as all users whose group\-id in
 179 the system's password database
 180 is equivalent to the \*(lqwheel\*(rq group.
 181 .SH "PROFILE COMPONENTS"
 182 .TP 20
 183 Aliasfile:
 184 Default alias file.
 185 .SH FILES
 186 .TP 20
 187 %etcdir%/MailAliases
 188 System-wide default alias file.
 189 .SH "SEE ALSO"
 190 .IR ali (1),
 191 .IR send (1),
 192 .IR whom (1),
 193 .IR getgrent (3),
 194 .IR getpwent (3),
 195 .IR conflict (8),
 196 .IR post (8)
 197 .SH BUGS
 198 Although the forward-referencing semantics of
 199 mh\-alias
 200 files prevent recursion, the
 201 .B alias\-file
 202 directive may defeat this.
 203 Since the number of file descriptors is finite, such
 204 infinite recursion will terminate with a meaningless diagnostic when
 205 all the fds are used up.
 206 .PP
 207 Earlier versions of this man page showed a semicolon at the end of the
 208 blind list example.  That caused the preceding alias to not be
 209 expanded.  There must not be a semicolon at the end of, or within, the
 210 address group of a blind list.
 211 .B post
 212 will append the semicolon to the blind list name.