PERL Miscellaneous - FAQ 8.43 How do I open a file without blocking?

Author

FAQ 8.43 How do I open a file without blocking?

PerlFAQ Server

2005-06-08, 8:58 am

This message is one of several periodic postings to comp.lang.perl.misc
intended to make it easier for perl programmers to find answers to
common questions. The core of this message represents an excerpt
from the documentation provided with Perl.

--------------------------------------------------------------------

8.43: How do I open a file without blocking?

If you're lucky enough to be using a system that supports non-blocking
reads (most Unixish systems do), you need only to use the O_NDELAY or
O_NONBLOCK flag from the Fcntl module in conjunction with sysopen():

use Fcntl;
sysopen(FH, "/foo/somefile", O_WRONLY|O_NDELAY|O_CREAT, 0644)
or die "can't open /foo/somefile: $!":

--------------------------------------------------------------------

Documents such as this have been called "Answers to Frequently
Asked Questions" or FAQ for short. They represent an important
part of the Usenet tradition. They serve to reduce the volume of
redundant traffic on a news group by providing quality answers to
questions that keep coming up.

If you are some how irritated by seeing these postings you are free
to ignore them or add the sender to your killfile. If you find
errors or other problems with these postings please send corrections
or comments to the posting email address or to the maintainers as
directed in the perlfaq manual page.

Note that the FAQ text posted by this server may have been modified
from that distributed in the stable Perl release. It may have been
edited to reflect the additions, changes and corrections provided
by respondents, reviewers, and critics to previous postings of
these FAQ. Complete text of these FAQ are available on request.

The perlfaq manual page contains the following copyright notice.

AUTHOR AND COPYRIGHT

Copyright (c) 1997-2002 Tom Christiansen and Nathan
Torkington, and other contributors as noted. All rights
reserved.

This posting is provided in the hope that it will be useful but
does not represent a commitment or contract of any kind on the part
of the contributers, authors or their agents.

xhoster@gmail.com

2005-06-08, 3:59 pm

PerlFAQ Server <comdog@panix.com> wrote:
> This message is one of several periodic postings to comp.lang.perl.misc
> intended to make it easier for perl programmers to find answers to
> common questions. The core of this message represents an excerpt
> from the documentation provided with Perl.
>
> --------------------------------------------------------------------
>
> 8.43: How do I open a file without blocking?
>
> If you're lucky enough to be using a system that supports
> non-blocking reads (most Unixish systems do), you need only to use
> the O_NDELAY or O_NONBLOCK flag from the Fcntl module in conjunction
> with sysopen():
>
> use Fcntl;
> sysopen(FH, "/foo/somefile", O_WRONLY|O_NDELAY|O_CREAT, 0644)
> or die "can't open /foo/somefile: $!":
>
> --------------------------------------------------------------------

I'm not sure I even understand what this is supposed to accomplish, but
wouldn't a better title be "How do I open a file for non-blocking reads?"?

As it stands, it sounds like it is the "open" (or "sysopen") itself that is
supposed to not block.

Xho

--
-------------------- http://NewsReader.Com/ --------------------
Usenet Newsgroup Service $9.95/Month 30GB

brian d foy

2005-06-08, 8:57 pm

In article <20050608122112.649$WX@newsreader.com>, <xhoster@gmail.com>
wrote:

> PerlFAQ Server <comdog@panix.com> wrote:

[color=darkred]
> I'm not sure I even understand what this is supposed to accomplish, but
> wouldn't a better title be "How do I open a file for non-blocking reads?"?

It might be. I've added the question to my queue and will think
about it when my brain isn't mush. :)

--
brian d foy, bdfoy@cpan.org
Subscribe to The Perl Review: http://www.theperlreview.com

Sponsored Links