Newsgroups: comp.unix.internals
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!uupsi!cmcl2!panix!zink
From: zink@panix.uucp (David Zink)
Subject: Re: Redirection of stderr
Sender: zink@panix.uucp (David Zink)
Message-ID: <1991Mar29.060051.15597@panix.uucp>
Date: Fri, 29 Mar 91 06:00:51 GMT
Organization: PANIX - Public Access Unix Systems of NY

In article <3181@inews.intel.com>, bhoughto@pima.intel.com,
           (Blair P. Houghton) sez:
 ( About using memcpy to duplicate FILEs )
>You're lucky, and probably don't close either of them, which
>closes both of them, regardless of whether a FILE object holds
>the state, because the kernel is now free to unlink the file.
(Given NFS, the kernal is _always_ free to unlink the file.)
>
>                               --Blair

I thought more fun was to close one and then open another file . . . .
   if ((fp = fopen("logfile", "a+")) != (FILE *)0)
   {
        setbuf(fp, (char *)0);
        memcpy((char *)stderr, (char *)fp, sizeof(*fp));
        fclose(fp);
   }
   if ((fp = fopen("database", "r+")) == (FILE *)0)
   {
        perror("database");/* May even succeed if it writes to fd 2 directly */
        exit(1);/*NOTREACHED*/
   }
   fprintf(stderr, "Beginning operations\n");
   . . .

Looks good to me!
      David
/*{fflush(a);close(fileno(a));fileno(a)=dup(fileno(b));} Works some places.*/
. . . if you must . . .