.\"	@(#)mesg.1	2.41
.\"
.TH MESG 1 "Jan 20, 2000"
.AT 3
.SH NAME
mesg \- permit or deny messages
.SH SYNOPSIS
.B mesg
[-s] [-v] [y|n|ye|ne|Y|N|NE] [d] [-p[w|t|k|a]] [-x[w|t|k|n]] [-m[l|c|a]] [-h[Y|y|n]] [-r[y|n]] [-b[y|n]]
.SH DESCRIPTION
This is the "Orville write" verison of the standard Unix
.I mesg
command.
.PP
.I Mesg
with argument
.B n
forbids messages via
.IR  write (1),
.IR ojot (1),
.IR tel (1),
and
.IR talk (1)
by revoking non-user
write permission on the user's terminal.
.I Mesg
with argument
.B y
reinstates permission.
All by itself,
.I mesg
reports the current state without changing it.
.PP
The
.B ne
and
.B ye
settings mean ``no with exceptions'' and ``yes with exceptions'' respectively.
If
.B ne
is set, and there is file named
.I .yeswrite
in your home directory,
then the users whose logins are listed there may still write you.
If
.B ye
is set, and there is a file named
.I .nowrite
in your home directory,
then the users whose logins are listed there may not write you.
These files have no effect if the permissions are set to
.B n
or
.BR y .
The
.I .nowrite
and
.I .yeswrite
files do not need to be permitted to anyone else,
and almost any plausible format will be understood
(listing one login name per line is a good default).
Lines may be commented out with a # sign in the first column.
.PP
The upper case
.B Y
and
.B N
do all that the lower case ones do, but may have some additional affects
depending on the installation.
.PP
The
.B N
argument, if enabled, will attempt to disconnect any write sessions currently
directed at your tty.
This is meant to allow users to slam the door on unwelcome writers.
Note that a simple ``mesg n'' will not stop anyone who is already writing
you from continuing to do so, it only prevents new connections from being
made.
The
.B NE
setting also causes a disconnect, but turns your settings to
.B ne
instead of
.BR n .
The
.B d
argument causes a disconnect, just like ``mesg N'', but does not change
your message permissions.
.PP
Normally 
.I mesg
always depermits your tty device, so you can only be written through
.I write
and similar programs.
This prevents arbitrary stuff from being redirected to your tty.
When you do ``mesg Y''
your tty is write permitted to others.
This is rarely necessary or desirable.
.PP
.I Mesg
can also be used to set other switches that affect Orville
.IR write (1).
The
.B -p
flag lets you set preferences to
(w) write, (t) telegrams, (k) talk, or (a) any.
The default is ``any.''
If you set a preference to write,
then people will not be able to send telegrams or talk requests to you.
If they try to send telegrams, they will be asked if they want to write
you instead.
Similarly if you prefer telegrams, people will not be able to write or talk to
you, and if you prefer talk, people will not be able to write or tel you.
You can designate two preferences, like ``mesg -pt -pw'' to allow people to
write or telegram you, but not make talk requests to you.
Alternately, you can use the
.B -x
flag to block particular programs.
Doing ``mesg -xk'' blocks only the talk program, and is equivalent to
``mesg -pt -pw''.
Similarly the ``-xn'' flag excludes no programs and is equivalent to ``-pa''.
Trying to block all programs just turns you permissions off.
.PP
The
.B -m
flag lets you set modes to
(l) line, (c) character, or (a) any.
The default is ``any.''
If you set a mode, then all writes to you will be done in that mode.
If you leave it as ``any,''
the choice is left to the writer.
This will not affect connections already in progress, only future ones.
.PP
The
.B -r
flag lets you turn on or off the recording to telegrams sent to you.
If it is enabled, everytime you are sent a telegram (or a write with
input taken from a file), the text of the messages is saved in a file
named .lastmesg in your home directory.  This allows you to redisplay
the last message sent to you using the
.IR huh (1)
command.
If a screen clear ate a telegram message before you had time to read it,
then the
.I huh
command lets you see it again.
Note that only the last message sent is stored.
The file is permitted to be readable to you only.
.PP
The
.B -b
flag lets you tell the
.I write
and
.I talk
programs whether or not to beep
when a person writes you or sends you a telegram.  The default is to beep.
.PP
The 
.B -h
flag lets you turn on or off your helper status.
People who designate themselves as helpers are announcing their
willingness to help out lost users.
Their accounts will be marked on the
output of the
.IR finger (1)
command, and if anyone does a
.I write
or
.IR ojot (1)
to ``help'' they automatically get connected to someone who has a help
flag set.
Normally, turning your permissions off also turns your helper-status off,
but if you set the
.I -h
flag to
.IR Y ,
then you will remain a helper even when your message permissions are off.
This means you can receive help requests, but not normal messages.
.PP
On some systems there is a restricted list of users who may be helpers.
This is usually kept in the file /etc/helpers, one login name per line.
If such a file exists then you will have to get the operators to add your
name to it to be able to designate yourself as a helper.
.PP
If no new settings are given to
.IR mesg ,
then it just reports on the current settings.
Normally it prints the message permissions, but if a
.BR -h ,
.BR -p ,
.BR -r ,
or 
.B  -m
flag was given without a new value after it, then the current status of
that switch will be printed instead.
If you use the
.B -s
flag, then this output will be suppressed.
The command still reports the status of the selected switch with its numeric
return code.
.PP
If you use the
.B -v
flag, all switch settings will be reported in a verbose mode.
.PP
The numeric values returned as return codes
(see below) can also be used to set switches.
Thus ``mesg 0 -m2'' sets permissions on, and the mode to any.
This makes it easy for shell scripts to restore settings that were stored
previously.
.PP
The argument syntax is actually a lot looser than mentioned above.
The dashes before options may be omitted,
Spaces may be added or omitted anywhere in the argument list.

.SH FILES
/dev/tty*
.br
/etc/wrttmp
.br
/etc/helpers
.SH "SEE ALSO"
write(1), amin(1), finger(1), huh(1), helpers(1), talk(1)
.SH DIAGNOSTICS
Exit status is -1 on an error.
Otherwise a code is returned reporting the status of one of the settings.
If the arguments included
.BR -h ,
.BR -p ,
or 
.B  -m
flags without a new value after it, then the last of these listed will be
reported.
Otherwise, if any options were set, the last of those listed in the argument
list will be reported.
And if nothing was set, then message permissions are reported.
.PP
When message permissions, record settings, or helper settings are reported,
0 indicates 'y', and 1 indicates 'n'.
When preferences are reported,
1 indicates 'w', 2 indicates 't', and 4 indicates 'k', and any combinations
are returned as sums of these values.
When modes are reported,
0 indicates 'l', 1 indicates 'c', and 2 indicates 'a'.
.SH BUGS
Turning off 'talk' permissions will only work if you have a talkd which has
been modified to understand Orville write's permission.