Re: MiNT bug

[Michael Hill <Michael_Hill@csgsystems.com>]

On Fri, Mar 27, 1998 at 07:29:52PM -0500, Martin-Eric Racine wrote:
> >On Fri, 27 Mar 1998, Martin-Eric Racine wrote:
> >>I was just writing this simple script, and it seems MiNT
> >>(or the shell?) doesn't understand the $TTY variable:
> >
> >tty in our case is a program that will fetch the current tty, 
>
>Sounds nice, except it doesn't excuse MiNT not supporting $TTY which
>is a standard Unix environment variable.

Oh, really??  Maybe under BSD...  But it's not defined in Solaris, and
therefore apparently not a required part of SVR4 *or* POSIX.  Besides, it
may be defined in /etc/profile; it probably *isn't* intrinsically defined
by the shell, or by /bin/login (pretty much the parent process of all
user processes).

And about K. Ellis's comments about daemons:  Daemons, by definition, are
supposed to run without being attached to any terminal.  Every process
inherits a session (as well as an environment) from its parent, and the
session ID, or SID, is the same for all children.  Part of the session is
the "controlling tty".  A daemon must execute the setsid() call to get a
new session for itself, and in the process the link to a controlling tty
is severed.  This is all documented very well in "Advanced Programming in
the UNIX Environment" by Richard Stevens.

This is why, when you do a 'ps', you will see that all the daemons
have "?" in the "TTY" column.

Note:  My comments are all about real UNIX; I know very little as of
yet about how MiNT implements UNIX functionality.

-- 
			--Michael

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