Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!snorkelwacker!mit-eddie!uw-beaver!apollo!oj
From: oj@apollo.HP.COM (Ellis Oliver Jones)
Newsgroups: comp.unix.wizards
Subject: Re: Job Control (a la csh/ksh) from within C
Message-ID: <46577568.20b6d@apollo.HP.COM>
Date: 20 Oct 89 14:57:00 GMT
References: <11237@smoke.BRL.MIL> <1989Oct6.164830.5856@utzoo.uucp> <1719@zen.co.uk> <1989Oct3.153120.4750@utzoo.uucp> <320@sopwith.UUCP> <10041@venera.isi.edu> <10163@venera.isi.edu>
Sender: root@apollo.HP.COM
Reply-To: oj@apollo.hp.com
Organization: Apollo Computer, Chelmsford, MA
Lines: 26

In article <10163@venera.isi.edu> raveling@isi.edu (Paul Raveling) writes:
>	An intriguing idea would be multiple interface layers
>	to support different dialects of Unix (Sys V, BSD, HP-UX,...)
>	on a per-job or per-process basis.

Intriguing indeed.  You could use an environment variable (SYSTYPE, say) 
to control, for each shell and process, which U***x variant was in force.
You could come up with a way to tag executable images with a RUNTYPE which
was distinct from the SYSTYPE, to allow program developers to work in
one environment and program users to work in another without excessive
confusion.  You could construct your file system so that directories 
like /usr contain soft links through the SYSTYPE environment variables,
like these:

lrwxrwxrwx   1 root           21 Oct 13 19:14 bin -> ../$(SYSTYPE)/usr/bin
lrwxrwxrwx   1 root           24 Oct 13 19:14 catman -> ../$(SYSTYPE)/usr/catman
lrwxrwxrwx   1 root           25 Oct 13 19:14 include -> ../$(SYSTYPE)/usr/include
lrwxrwxrwx   1 root           21 Oct 13 19:14 lib -> ../$(SYSTYPE)/usr/lib

and the actual /usr/bin files could really be found, in several flavors, in
places like /bsd4.3/usr/bin and /sys5.3/usr/bin .   Great idea!  

I didn't have to laboriously fake the above directory listing.
Rather, I just asked my computer for it.

/Ollie Jones (speaking for myself, not necessarily for HP's Apollo Systems Division)