Linux Users' Group of Davis (LUGOD): Mailing List Archives - Re: [vox-tech] Permission Denied Error

On Fri, Jul 9, 2010 at 11:07 AM, Matthew Holland <mdholland@ucdavis.edu> wrote:

It seems pretty clear to me from the OP's further clarifications that
this is a header file that belongs to a third party application, and
the effects of editing the header file in question are known to the
poster. The OP's lack of familiarity with UNIX comes through, and I
think this is rousing everyone's protective instincts. Fine, but this
all probably resulted from untarring the source code with sudo in the
first place, so I think we can all just calm down with the warnings.

I should add that I screwed up the chown command in my first response.
It should be "chown username file" instead of "chown file username."
Sorry for any confusion.

I would recommend the the OP that if you're going to be using a Mac
for this sort of thing, you do some reading on general UNIX use and
administration. And learn to read man pages, if you don't know
already. All will become clear in good time.

Matt

On Fri, Jul 9, 2010 at 10:59 AM, Bill Kendrick <nbs@sonic.net> wrote:
> On Thu, Jul 08, 2010 at 10:19:00PM -0700, Jeff Newmiller wrote:
>> Unless you have the full source code and are familiar enough with it
>> to insure that it doesn't have hidden dependencies on those constants,
>> and are recompiling the full source code, you should still be wary of
>> changing read-only headers.
>
> Indeed.
>
> Furthermore, a more proper way of altering constants for your own
> app's purpose would be to redefine them in your source, rather than
> alter the library's header file.
>
> e.g.:
>
> #include <some_library_header.h>
>
> #if defined(SOMECONST)
> #undef SOMECONST
> #end
>
> /* Override some_library_header.h's SOMECONST with my own number */
> #define SOMECONST 1234
>
>
> Obviously, this changed constant will only be visible to the file(s)
> that see the above C preprocessor commands.
>
> But do keep in mind, as explained earlier, even if you change some
> #define's _in the system-wide header file_ (e.g., if I go in and
> screw around with "/usr/include/stdio.h"), those changes will only
> affect:
>
> * programs compiled with that header
> * and compiled AFTER I edited it
>
> The "stdio" library itself, and any applications which were compiled
> against the "stdio.h" header prior to my edits, will REMAIN UNCHANGED.
>
>
> I'm throwing these caveats in here because I think we still don't
> know exactly what you're trying to accomplish. :) Based on the vague
> requirement of "need to change numbers in a header file", what you're
> trying to do could range from trivial to impossible to downright
> dangerous. :)
>
>
>
> -bill!
> _______________________________________________
> vox-tech mailing list
> vox-tech@lists.lugod.org
> http://lists.lugod.org/mailman/listinfo/vox-tech
>
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