VMS shell under Unix (was: Re: why learn UNIX)

[mouse at mcgill-vision.UUCP]

In article <3700003 at hpfcph.HP.COM>, dalem at hpfcph.HP.COM ( Dale McCluskey) writes:
> [discussion of emulators on various systems, etc.]

> If one looks at the microfiche source for DCL, they are using an
> undocumented call to run programs.  If you call DEC and ask about it,
> they will deny its existence.

I didn't know *that*.  Yech.

> This leaves Joe Hacker with the choice of LIB$SPAWN or SYS$CREPRC for
> doing his fork()/exec().  Both are horribly slow.

$IMGACT (or was it $IMGSTA?) does not do a fork/exec, it just does the
exec.  The image being run runs in the *same process* as the CLI
("shell").  This is a major difference of philosophy; under VMS your
process has a CLI in P1 space which runs programs in P0 space, one at a
time.  Under UNIX the shell is running just as if it were a normal user
program is (which it in fact is, or at least was before the recent
getusershell() nonsense came along [mutter, grumble]).

> VMS has some nice features (a good backup/restore facility,

Needed.

> the ability to rename a directory as a Joe User,

UNIX has this, at least modern UNIX.  rename() works on directories
(without needing privilege).  I don't know whether USG UNIX has
anything like rename(), but if they don't, well, that's just another
thing wrong with USG UNIX, no?

> the ability to refer to the current directory and everything below
> it,

Or any directory and everything below it, for that matter.  However,
this would be easy to put into the shell's globbing routines.  Most
applications of it can be better addressed with find and xargs, which
may explain why it isn't there already.

> etc.

You missed just about the only VMS thing I miss:  the debugger.  VMS
had a *good* debugger, certainly better than anything I've seen on
UNIX.

					der Mouse

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