S/390: The Linux Dream Machine
But It's Still Not Linux!

Scott Courtney
Wednesday, February 23, 2000 09:19:48 AM
If you've read all that came before, you have probably decided
by now that I am some kind of mainframe bigot, that I'm one of those people who
likes to sit in a glass room with a raised tile floor and sneer at the little
toy PCs. Actually, quite the opposite is true. I am a PC maven through and
through. I got started in computers by designing my own 8080A system and I will
never willingly give up the responsiveness, flexibility and control that I
have with a standalone CPU.
Besides, for all their awesome power and scalability, the truth
is that I don't like the command shells that are standard on either VM
or OS/390. VM has a thing called Conversational Monitor System, or CMS, and
OS/390 offers Time Sharing Option, or TSO. I've used both for years, and they
are immensely capable environments. I can't knock either of these for power or
quality, but their command syntax just doesn't feel as elegant to me as does
the UNIX/Linux shell. Call it personal preference, but I really love things
like command substitution and environment variables, and the fact that the
shell is itself a programming language so I can do for and
while loops interactively. CMS and TSO can run REXX programs or
scripts, but with bash or ksh you live inside a script
all the time. VM has a thing called "CMS Pipelines," and it's truly
awesome in what it can do. VM/Pipes is sort of like all of the standard UNIX
text commands (head, tail, cut, grep,
tr, and so on) rolled into one. But in my opinion it's not quite as
seamless as the simple use of the vertical bar in Linux to imply I/O
redirection. And I have never cared for the 3270 terminal's insistence on
processing data screen-by-screen rather than character-by-character. I know why
they do it--better system performance for data entry--but that doesn't mean
I have to like it.
Driving bash feels like being in a snappy European
sports car, while CMS feels like being in a solid, luxurious Lincoln Town Car.
I just happen to like the sports-car feel better; as I said, it's just personal
preference. But ever since I began to hang around with my company's mainframe
gurus, and truly begin to understand just what a powerhouse that big iron
really is, I've secretly longed for the day when I could have the best of both.
I want nothing less than the sheer might of a mainframe combined with the
nimbleness of the Linux shell. I thought it was in my grasp when IBM released
the UNIX System Services feature on VM Open Edition, which includes a
POSIX-compliant environment that runs inside VM. It was pretty good, but it
didn't quite measure up to my expectations for a variety of reasons.
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