Question about dup()

[Mark Valentine]

I came across the following code fragment, and was wondering about its
history...  It's not mentioned in any of the manuals I've looked at.

        #define DUPFLG  0100

	    ...

        dup(f1 | DUPFLG, f2);

There was some parallel code (the other half of an #ifdef RES) which used
a F_GETFD/F_DUPFD/F_SETFD sequence instead, so I guess that this must be
somebody's way of saving the close-on-exec flag across a dup.

	Can anyone offer some enlightenment?

		Mark.
__
Mark Valentine, Spider Systems Limited, Edinburgh, UK.		/\oo/\
<mark at spider.co.uk, mark%spider.co.uk at uunet.uu.net, uunet!mcvax!ukc!spider!mark>