Interactive Background Processes

[wilber at alice.UUCP]

Greg Woods writes:
>In article <8029 at alice.UUCP> wilber at alice.UUCP writes:
>>As a non-wizard (posting under false pretenses, I guess) it seems to me that
>>if you have a version of Unix without job control or layers or the like the
>>"poor man's solution" to this problem is to fire up Emacs, make as many shell
>>buffers as you need, and run whatever you want in each one.  Of course the
>>background process can't keep running after you log out.
>
>Unfortunately, a Unix without job control, layers, or such will not
>provide the system facilities required for emacs to do the same.

The Unix running on my 3b1 (a somewhat bowdlerized variant on SYS V 2.0)
definately does not have job control (sigh) and, although there may be some
version of layers available for this box, I don't have it.  Nonetheless my
Emacs (GNU, version 18.49) runs multiple shell buffers just fine, thank you.
It communicates with the shell processes via ptys.  (The pty drivers I use are
a public domain version snarfed off the net.)  I haven't looked at the code to
see the details of how Emacs does it, but it works.  I suspect that whenever
Emacs has nothing better to do it simply polls the screen to see what to pass
to the ptys and polls the ptys to see what to put on the screen, but like I
said, I haven't bothered checking the code.

>Fortunately, one of these "features" usually exists in every version of
>Unix, though that doesn't mean emacs will work with it properly.

See above.  Emacs doesn't need job control or layers to handle multiple shells,
although at least on the 3b1 it does need ptys (attempting to link up with
shell processes via pipes didn't work).

>Unfortuantely, only a true window manager for X or NeWS, or layers (not
>shell-layers) on a DMD terminal, or something similar, are easy enough
>to use.  None of these are usefull on a dumb terminal at 1200 baud,
>though layers is nearly so, it's just the terminal isn't very cheap nor dumb.

Emacs isn't that tough to figure out -- no mice to slow you down, no cute
little bit mapped pictures of trash cans or rolodexes to confuse and distract
you.  Remember, Emacs, like Unix, is asymptotically user friendly.  And it can
be used at 1200 baud if you're desperate, although that is admittedly very
painful.  (I didn't realize you were stuck with a 1200 baud link.)

Bob Wilber   Work: UUCP: {allegra, mtune, ihnp4}!gauss!wilber
                   ARPA: wilber at research.att.com