Date: Fri, 27 Mar 2009 21:30:26 +0100 From: Tobias Rehbein <tobias.rehbein@web.de> To: Joost Bekkers <joost@jodocus.org> Cc: freebsd-questions@freebsd.org Subject: Re: [perl] sysopen(CD, "/dev/cd0", O_RDONLY | O_NONBLOCK) fails Message-ID: <20090327203026.GA50021@sushi.pseudo.local> In-Reply-To: <1772.192.168.100.227.1238185193.squirrel@jodocus.org> References: <20090326212045.GB3134@sushi.pseudo.local> <20090326221128.3a6d648f@gluon.draftnet> <20090327185912.GA77908@sushi.pseudo.local> <1772.192.168.100.227.1238185193.squirrel@jodocus.org>
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Am Fri, Mar 27, 2009 at 09:19:53PM +0100 schrieb Joost Bekkers:
> On Fri, March 27, 2009 19:59, Tobias Rehbein wrote:
> > Am Thu, Mar 26, 2009 at 10:11:28PM +0000 schrieb Bruce Cran:
> >>
> > Hm. Tried this and got ineresting results:
> >
> >> use POSIX;
> >> sysopen(CD,"/dev/cd0", O_RDONLY|O_NONBLOCK) || perror("sysopen")
> > works fine, but
> >> use POSIX;
> >> sysopen(CD,"/dev/cd0", O_RDONLY|O_NONBLOCK)
> >> print "$!"
> > prints "No such file or directory"
> >
> > Well, I think I'll have to accept that sysopen works but $! does not...
> > After
> > all sysopen is more important to me ;)
>
> As the perlvar manpage tells us:
>
> $! If used numerically, yields the current value of the C "errno"
> variable, or in other words, if a system or library call fails,
> it sets this variable. This means that the value of $! is
> meaningful only immediately after a failure.
>
> The value of $! is NOT an indicator of success or failure. It only tells
> you why something failed. If something succeeded $! is usualy left
> untouched.
Yes, that sounds sensible. Thanks for clarification.
--
Tobias Rehbein
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