Date: Fri, 28 Jul 1995 20:19:25 -0500 (CDT) From: Peter da Silva <peter@bonkers.taronga.com> To: jkh@time.cdrom.com (Jordan K. Hubbard) Cc: hackers@freebsd.org Subject: Re: your mail Message-ID: <199507290119.UAA13323@bonkers.taronga.com> In-Reply-To: <8635.806962669@time.cdrom.com> from "Jordan K. Hubbard" at Jul 28, 95 01:17:49 pm
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> > > > I disagree. Oh, not in the user interface model, but in the file system
> > > > and process model. It takes the UNIX "everything is a file" a logical
> > > > evolutionary step forward.
> > > Oh great. One of UNIX's worst abortions, taken to extremes (can you
> > > say "ioctl() is a bogus ``API'' for controlling behavior?" I thought
> > > so)..
> > Plan 9 doesn't have IOCTL at all. Just about everything is done with open,
> > close, read, and write.
> So how do you do "out of band" operations, like telling a tape
> drive to skip forward to the next mark?
The tape has a "data" and a "control" device. You write commands to the
control device.
You can read all the Plan 9 papers at plan9.att.com, and there's a lot of
very interesting stuff in there. For example, mounts are local to the
process, like current directory and environment variables are for UNIX.
So when a program is running under 8 1/2 it has a set of devices for the
screen and mouse visible. When you run 8 1/2, it opens the *same* devices,
so you can run 8 1/2 in a 8 1/2 window...
One of the devices is /dev/bitblt.
Backups are handled the same way, and you can do things like:
find 1995/07*/sys/src/cmd -name '*.c' | xargs grep -i bug
If you want to work on the system as it was in July 1995, you do:
bind("1995/0701/sys/src", "/sys/src", REPLACE)
...
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