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   1 This file contains some notes on features/bugs/etc which are
   2 not documented in the "MH User's Manual", as well as some notes
   3 on future directions.  See MHgenerate for more info.  Some of
   4 these notes assume VAX/V7 UNIX--as noted by {V/V7}.
   5
   6 0) Directories:
   7         support contains files which get copied to /etc/mh, as
   8                 well as some miscellaneous Rand support programs
   9         subs    contains support subroutines--built into subs.a
  10         strings contains c files which define all of the default
  11                 names and paths used by the package->strings.a
  12         Extras  old and un-supported code--much of it not
  13                 converted to V7.  Look at libg/libh for help in
  14                 getting around V7 features.
  15         DOC     contains the MH User's Manual document in nroff/
  16                 troff form.  This requires the Phototypesetter or
  17                 V7 version of nroff/troff, AND the Berkeley -me
  18                 macros.
  19
  20 1) Undocumented Feature:  The paths to the various programs which
  21    MH exec's are kept in variables named something like "lsproc".
  22    (See the strings directory.) While reading in the user's
  23    profile, (m_getdefs()) a component matching one of these exec
  24    path names, will cause the default string to be replaced by
  25    the profile entry argument.  Thus, the profile entry "lsproc:
  26    /usr/foo/bin/newls" will cause all MH programs using "lsproc"
  27    to get a new ls.  At least for now, there is no way to specify
  28    switches.  This mapping is arranged by the "procs" structure
  29    in m_getdefs.c--keep it up to date if new exec procs are
  30    added.
  31
  32 2) Collision:  Take a close look at the "onceonly" entry of the
  33    Makefile.  Bell already has a program named `file', which the
  34    makefile will rename to `filetype', which is what it tries to
  35    indicate.  If you really want to, you might rename the MH
  36    command `file', but I have yet to hear of an even vaguely
  37    reasonable alternative.
  38
  39 3) Different Approach:  Using the Berkeley C shell (csh),
  40    "multiple links to the same file with different profile
  41    entries" is better served with aliases.
  42
  43 4) Collision: {V/V7} BELL mail cannot co-exist with MH--IF THEY
  44    SHARE THE SAME MAILBOXES, otherwise they co-exist fine!  If
  45    you use the standard (VAX) mail directory /usr/spool/mail for
  46    MH, you should also install the MH version of the mail
  47    program.  It is much nicer, and integrates with MH cleanly.
  48    The advantage of using /usr/spool/mail is that login will
  49    notify of new mail.
  50
  51 5) Feature: If you add a line like:
  52
  53         30 1 * * * /etc/mh/conflict -mail admin
  54
  55    to crontab, then every morning at 1:30 AM, the alias file will
  56    be checked against the /etc/passwd file to see that
  57    inconsistencies haven't been introduced.  In particular, a
  58    line in the alias file may be "tom: jones" (because Tom Jones
  59    likes to be called Tom), but if tom is also a valid user name,
  60    tom will no longer receive any mail!  This program also prints
  61    any mail drops in /usr/spool/mail which don't belong to a
  62    valid user (i.e. a deleted or renamed user id).
  63
  64    "convlict -mail name" will check the consistency and mail
  65    the specified user a short status message.
  66
  67    This program also checks to see if there are any users who do
  68    not belong to any group, or any user in a group which is missing
  69    from the passwd file.  This latter is an inconsistency on all
  70    systems, whereas the former is not required except at Rand, and
  71    won't be compiled without the "-DRAND" cc flag in the makefile.
  72
  73 6) Hidden Feature:  At the request of some of the Rand staff,
  74    there is the ability to invoke a user-specified deletion-
  75    program to implement message deletion, rather than getting the
  76    default comma renaming convention (see next item).  If a
  77    user's profile contains the line: "Delete-prog: path", the
  78    specified path will be called with a list of files needing
  79    deletion.  All this code works...
  80
  81 7) Feature:  When a message (draft or in a folder) is "removed",
  82    it is really renamed with a leading comma.  E.g. foo -> ,foo.
  83    At Rand we have a program called the midnight skulker which
  84    goes through the whole system and removes all backup (starting
  85    with comma), a.out, and core files.  This backup convention
  86    gives users a chance to undo spurious removes, at least all
  87    day.  You may want to replace these renames with a simple
  88    unlink(), or each user may get this effect by specifying
  89    "Delete-prog: /bin/rm" in his/her profile.
  90
  91 8) Feature:  NEWS.  The news facility is undocumented in the MH
  92    manual, because it is a very new addition to the package.  SO,
  93    here it is...
  94
  95         The directory /usr/news should be created--it will
  96         contain the folders for news topics, and various support
  97         files.  The news items are strictly MH folders, and users
  98         can utilize all of the MH commands on them.  The news
  99         program is similar to "show", but it shows `unseen' news
 100         as the default, keeping a separate entry in the users
 101         profile for each news topic indicating the highest item
 102         the user has seen.  These entries look like
 103                 "news-<topic>: highest-seen".
 104
 105         Rather than read through the news folders to determine
 106         the number of entries, a file with name .<topic> (i.e.
 107         period followed by the topic name) is kept with length
 108         equal to highest message number.  Thus, to determine if a
 109         user hasn't seen some news, the news directory
 110         (/usr/news) is read, and for each non-period beginning
 111         file (i.e. each folder), stat the associated period
 112         beginning file, and compare its length with the users
 113         profile news entry for the same name.  If the user has no
 114         entry, or it is less than the length of the period-file,
 115         then show him the remainder of the news in each such
 116         topic.
 117
 118         The program `l' is used to display each message, and the
 119         highest item profile entry is updated prior to each
 120         individual message displayed, so <del> will leave the
 121         user's profile in the proper state for the next news
 122         request.
 123
 124         Add a user to the system called news, with home directory
 125         /usr/news and add the line:
 126
 127                 news.*: news
 128
 129         to /etc/MailAlias.  Thus, to add news to a topic, it is
 130         only necessary to mail to news.topic, and it will happen.
 131         To make the automatic filing into folders happen, copy
 132         the file support/news-mh_receiv to /usr/news/.mh_receive.
 133         This is a shell script which will get invoked whenever
 134         mail is sent to the user news (see next "undocumented
 135         feature").
 136
 137         Problems:  I have yet to write the program which packs
 138         news folders.  Items can be readily removed (as long as
 139         they are not the last item in the folder), but if the
 140         folder is packed (after some months/years the item
 141         numbers will reach the 999 limit), it is necessary to go
 142         through everyones .mh_profile files and reset the
 143         highest-seen numbers.  Not hard to write, I just haven't
 144         done it yet.  Also, the receive shell script should be
 145         recoded in C to speed it up considerably.
 146
 147 9) Undocumented Feature:  If a user has an executable program or
 148    shell script named ".mh_receive" in his home directory, then
 149    it will be executed by the mail deliverer RATHER than
 150    appending mail items to the user's mail file
 151    (/usr/spool/mail/name).  This program will be called with:
 152
 153         execlp(prog, prog, tmpfil, mail, home, 0);
 154
 155    where prog is the receive program, tmpfil is a file in
 156    /usr/tmp which is the mail to be received, mail is the path of
 157    the user's mail drop (/usr/spool/mail/name), and home is the
 158    $HOME directory of the user.  File descriptor 3 will have
 159    tmpfil opened on it read only.  These are all the RECEIVER'S
 160    parameters, not the sender's.  Also, the environment is set up
 161    with appropriate values for HOME and USER.
 162
 163    Eventually, the goal is to have received mail LINKED into
 164    user's inbox folders, rather than appended to their mailboxes.
 165    This will facilitate the sending of mail to large distribution
 166    lists (Rand is always tight on space!) Have a look at the news
 167    .mh_receive file for an example of this facility.
 168
 169    Warning: appropriate interlocks are implemented in "deliver"
 170    to prevent collisions when it appends to mailboxes, but it is
 171    up to the users's .mh_receive program to provide its own
 172    interlocks!
 173
 174 10) New Program: "mhl" is a custom MH list program which displays
 175    messages according to a format specification.  See MHL.Design
 176    for further details.  See Extras/mhl.bsb for an added example.
 177
 178 11) New Program: "ali" is a mail alias checker.  It takes a list
 179    of names, and produces the alias list for the names.  It also
 180    indicates any names which are not valid local names or aliases.
 181
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 184
 185 Bruce Borden
 186 Mar