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From:
[email protected] (David M. Sundstrom)
Subject: Re: checking whether information is waiting in
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[email protected]>
Sender:
[email protected]
Nntp-Posting-Host: enterprise.asic.sc.ti.com
Reply-To:
[email protected]
Organization: Texas Instruments
References: <
[email protected]>
Date: Thu, 18 Nov 1993 15:09:18 GMT
Lines: 38
In article
[email protected],
[email protected] (Jonathan Monsarrat) writes:
> Hi!
>
> I have some a perl program that reads from a pipe, so FILEHANDLE is data being
> generated on the fly.
>
> I'd like to be able to check whether any data is pending reading on FILEHANDLE.
>
> Can it be done in Perl?
>
> -Jon
> p.s. yes, of course it can, and there's more than one way to do it! :)
You can use the select call:
vec($rin,fileno(FILEHANDLE),1)=1;
if(select($rout=$rin, undef, undef, 0)) {
## data is ready
} else {
## data is not ready
}
By changing the 4th argument of select to a nonzero number, you will block
your process until a) data is ready or b) it times out according to the
value you specified. A timeout of zero effects a poll.
For more on select, see the Camel book. To understand the "vec" wizardy,
browse the man page on select to understand the format of the arguments
which you are passing it.
-David Sundstrom <
[email protected]>
Texas Instruments.
