@node dup2
@section @code{dup2}
@findex dup2

POSIX specification:@* @url{http://www.opengroup.org/onlinepubs/9699919799/functions/dup2.html}

Gnulib module: dup2

Portability problems fixed by Gnulib:
@itemize
@item
This function always returns 0 for success on some platforms:
mingw.

@item
This function can hang when duplicating an fd to itself on some platforms:
mingw.

@item
This function returns 0 for @code{dup2 (1, 1)} on some platforms:
Cygwin 1.5.x.

@item
This function may return @code{-EBADF} instead of @code{-1} on some platforms:
Linux releases between July 2008 and May 2009 (versions 2.6.27 to 2.6.29).

@item
This function returns @code{EMFILE} instead of @code{EBADF} for
extremely large targets, which interferes with using
@code{dup2(fd,fd)==fd)} as the minimal @code{EBADF} filter:
FreeBSD 6.1, Cygwin 1.5.

@item
This function is missing on some older platforms.
@end itemize

Portability problems not fixed by Gnulib:
@itemize
@end itemize
