NAME
mesg - permit or deny messages
SYNOPSIS
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]]
DESCRIPTION
This is the "Orville write" verison of the standard Unix mesg command.
Mesg with argument n forbids messages via write(1), ojot(1), tel(1),
and talk(1) by revoking non-user write permission on the user’s
terminal. Mesg with argument y reinstates permission. All by itself,
mesg reports the current state without changing it.
The ne and ye settings mean ‘‘no with exceptions’’ and ‘‘yes with
exceptions’’ respectively. If ne is set, and there is file named
.yeswrite in your home directory, then the users whose logins are
listed there may still write you. If ye is set, and there is a file
named .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 n or y. The .nowrite and .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.
The upper case Y and N do all that the lower case ones do, but may have
some additional affects depending on the installation.
The 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 NE setting
also causes a disconnect, but turns your settings to ne instead of n.
The d argument causes a disconnect, just like ‘‘mesg N’’, but does not
change your message permissions.
Normally mesg always depermits your tty device, so you can only be
written through 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.
Mesg can also be used to set other switches that affect Orville
write(1). The -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 -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.
The -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.
The -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 huh(1) command. If a
screen clear ate a telegram message before you had time to read it,
then the 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.
The -b flag lets you tell the write and talk programs whether or not to
beep when a person writes you or sends you a telegram. The default is
to beep.
The -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 finger(1) command, and if anyone does a write or 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 -h flag to 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.
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.
If no new settings are given to mesg, then it just reports on the
current settings. Normally it prints the message permissions, but if a
-h, -p, -r, or -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
-s flag, then this output will be suppressed. The command still
reports the status of the selected switch with its numeric return code.
If you use the -v flag, all switch settings will be reported in a
verbose mode.
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.
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.
FILES
/dev/tty*
/etc/wrttmp
/etc/helpers
SEE ALSO
write(1), amin(1), finger(1), huh(1), helpers(1), talk(1)
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 -h, -p,
or -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.
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’.
BUGS
Turning off ’talk’ permissions will only work if you have a talkd which
has been modified to understand Orville write’s permission.