Re: building rc on QNX4

[David Luyer <david_luyer@pacific.net.au>]

Tim Goodwin wrote:
> >                                                                  another
> > one is whether it will ever make it possible not to export everything to
> > the environment by default.
> 
> I brought this up a few months ago, and the consensus seemed to be that
> the current scheme works well enough in practice.  Have you encountered
> a problem?

I encountered a problem with this years ago but just started using
"su -" when I was trying to get programs to run that it broke.

Basically some OS's (Digital Unix for one I think) have C libraries which
choke horribly if the size of the command line + environment array is greater 
than a certain value, and if you have a number of complex functions in your 
shell this value (64k?) can be a pain.

Although it is really useful to have the shell functions inherited by a shell 
which was spawned from some unrelated program running under the initial shell,
maybe we need some way to prevent this in specific cases?

Maybe some syntax along the lines of:

(+ HOME PATH path USER LOGNAME "fn "*) /usr/sbin/cron &

to pass HOME, PATH, path, USER, LOGNAME and fn_* only

(- "fn "*) /usr/sbin/cron &

to pass everything but fn_*

But then - as with most things this could be done in a function

eg: run sh with HOME USER LOGNAME
    run sh without "fn "*

which could be implemented relatively easily if there was an option to whatis 
to just list variables instead of show what they are.

(eg: "whatis -fq" - list functions, "whatis -vq" - list variables)

Anyway - basically - I think it might be more useful to extend whatis such
that it can be used to implement easily a facility to run a command without 
any environment variables, rather than to actually implement that facility 
internally.

David.
-- 
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David Luyer
Senior Network Engineer
Pacific Internet (Aust) Pty Ltd
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