[perl] sysopen(CD, "/dev/cd0", O_RDONLY | O_NONBLOCK) fails

[Tobias Rehbein]

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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