Re: Proposal for write(1) addition

[Robert Elz <kre%munnari.OZ.AU@localhost>]

    Date:        Sat, 17 Sep 2011 02:20:07 +0200
    From:        Julian Fagir <gnrp%komkon2.de@localhost>
    Message-ID:  <20110917022007.402466df@adolfputzen>

  | according to somebody from the #tmux-channel in freenode, tmux does not set
  | utmp entries because they would need additional permissions for that.

If that is the reason, then it also cannot chown the pty to be owned
by the user, which would make the modification to write(1) suggested
useless, and also prevent the user from disabling permission for others
to write.

But if tmux is able to chown ptys, which I assume it must be for your
proposal to make any sense at all, then it certainly can also create
a utmp entry if it wants to - having permission to chown a file (/dev/...
in this case) away from root, to some other user is certainly sufficient
permission to write into utmp (not necessarily true in the converse.)

  | With the patch, only the newest active terminal is used.

Which would be the most obnoxius behaviour I can imagine.  That's
where I'm working (most probably) not where I want noise from some
random idiot who just learned the write command and wants to try it out.

  | Not having a utmp-entry is imho the wrong way of staying private - and in
  | most cases it's not even possible.

I haven't found such a case, just about everything (other than login itself)
that has the ability to write in utmp has an option to prevent that, but
almost none of them (perhaps absolutely none of them) have an option for ...

  | That's exactly what mesg is for.

and yes, that is the ideal way, but annoying difficult right now.

kre