Re: building rc on QNX4

["Smarasderagd" <smarry@vex.net>]

David Luyer <david_luyer@pacific.net.au> writes:
>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.

In some cases this limit is enforced by the operating system; execve() chokes
on Linux if the arguments plus environment exceed (I think) 128K.

>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.

If you don't need to export anything but non-array variables, the "-i"
or "-" option to "env" does what you want.  For the other cases:

You could have a whatis option (or a gnarly function that understands
enough rc syntax not to be fooled by newlines in quoted strings) that
spews null assignments / definitions for everything, and then eval the
result filtered for the things you want to preserve, but eeuugh.  If a
function is that big it won't be much slower if it's a script instead.