Date: Tue, 7 Dec 1993 11:42:50 -0500 (EST)
From: Edwin L Phillips Jr <flaregun AT strauss DOT udel DOT edu>
Subject: Re: Symbolic links and functionality [ was: O_BINARY ]
To: DJGPP mailing list <djgpp AT sun DOT soe DOT clarkson DOT edu>

On Tue, 7 Dec 1993, DJ Delorie wrote:

> > /* DODAT.C */
> > #include <stdlib.h>
> > void main(int argc, char *argv[])
> > {
> > 	execv("DOIT.EXE", argv[]);  /* or another flavor of exec() */
> > }
> >
> >   DOIT.EXE will see that argv[0] = "DODAT.EXE", won't it?  This seems to 
> 
> No.  argv[0] is *always* set from the program name in MS-DOS,
> regardless of what you pass for exec*.  DJGPP bypasses MS-DOS in order
> to provide this functionality, so if you were using a djgpp program to
> call another djgpp program (via exec*), the argv array is passed
> intact.  Note, however, that it's much more efficient to use the
> symbolic link mechanism that djgpp provides instead.
> 

  If I am following this, you are saying this WILL work between programs 
compiled with DJGPP.  For example:

/* DOIT.C */
void main(int argc, char *argv[])
{
	printf("%s\n", argv[0]);
}

would print DOIT.EXE when invoked from the DOS prompt, and DODAT.EXE when 
it is execv'd in the DODAT.C program. (??)

  But, if you invoke, say, a program compiled with BCC (or other)

	execl("mybccprg.exe", "yomama.exe", "arg1", "another arg", 0);

it would call mybccprg.exe with argv[0] = "mybccprg.exe", instead of 
"yomama.exe" (??).  Kinda like

	system("yomama.exe arg1 'another arg'");

  Thanks DJ,
  Ed

(in high density brain fog, low sleep mode)

/***************************************************************************/
/* Ed Phillips  flaregun AT brahms DOT udel DOT edu       University of Delaware      */
/* Jr Systems Programmer  (302) 831-6082       NSS/Software Systems        */
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