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From: Mark Hobley on 27 Feb 2010 21:08
In comp.os.linux.development.apps Mark Hobley <markhobley(a)hotpop.donottypethisbit.com> wrote:
> Right. That is just as messy as __dead. I think I will just delete the tag.

Right I have found another doubleunderscore thingybob. This time __progname:

void
usage(void)
{
extern char *__progname;
(void)fprintf(stderr, "usage: %s [-itw] file ...\n", __progname);
exit(1);
}

This was easier to find in google than the last one. I stumbled across:

http://stackoverflow.com/questions/273691/using-progname-instead-of-argv0

This tells me that __progname is a bsdism and getopt() modifies argv[],
which is not available outside of main(). I guess that I need to somehow
capture argv[0] on entry to main. I guess that the following is a fixup for
this:

extern char *progname;

int
main(int argc, char *argv[])
{
extern char *progname;
progname=argv[0];
blah blah blah
}

void
usage(void)
{
extern char *progname;
(void)fprintf(stderr, "usage: %s [-itw] file ...\n", progname);
exit(1);
}

Does that look right?

Mark.

--
Mark Hobley
Linux User: #370818 http://markhobley.yi.org/

From: William Ahern on 28 Feb 2010 14:22
In comp.lang.c Mark Hobley <markhobley(a)hotpop.donottypethisbit.com> wrote:
> In comp.os.linux.development.apps Mark Hobley <markhobley(a)hotpop.donottypethisbit.com> wrote:
> > Right. That is just as messy as __dead. I think I will just delete the tag.

> Right I have found another doubleunderscore thingybob. This time __progname:

> void
> usage(void)
> {
> extern char *__progname;
> (void)fprintf(stderr, "usage: %s [-itw] file ...\n", __progname);
> exit(1);
> }

> This was easier to find in google than the last one. I stumbled across:

> http://stackoverflow.com/questions/273691/using-progname-instead-of-argv0

If you're only porting to Linux you can either use the getprogname()
implemented in libnostd, or just read over the code in
bsd/stdlib/getprogname.h.

For Linux (or rather glibc and compatible libraries) the simple substitute
is `extern char *program_invocation_short_name'.
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