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From: jpr@jpradley.jpr.com (Jean-Pierre Radley)
Newsgroups: comp.unix.wizards
Subject: Re: dup2
Message-ID: <1991Feb08.201602.3392@jpradley.jpr.com>
Date: 8 Feb 91 20:16:02 GMT
References: <27B1CA1C.22559@ics.uci.edu>
Reply-To: jpr@jpradley.UUCP (Jean-Pierre Radley)
Distribution: usa
Organization: NYC Public Unix
Lines: 20

In article <27B1CA1C.22559@ics.uci.edu> schmidt@ics.uci.edu (Doug Schmidt) writes:
>	I'm curious, is it possible to implement the dup2() system
>call using only routines available in the standard C library and other
>existing system calls?

From the xcmalt sources:

#if !DUP2		/* For those that do not have dup2() */
#include <fcntl.h>
dup2(oldfd, newfd)
int oldfd, newfd;
{
   if (fcntl(oldfd, F_GETFL, 0) == -1)      /* Valid file descriptor? */
       return (-1);                         /* No, return an error */
   close(newfd);                            /* Ensure newfd is closed */
   return (fcntl(oldfd, F_DUPFD, newfd));   /* Dup oldfd into newfd */
}
#endif /* !DUP2Thanks to Bill Allie CIS: 76703,2061 */

 Jean-Pierre Radley   NYC Public Unix   jpr@jpradley.jpr.com   CIS: 72160,1341