[32255] in Perl-Users-Digest
Perl-Users Digest, Issue: 3522 Volume: 11
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Mon Oct 17 09:09:22 2011
Date: Mon, 17 Oct 2011 06:09:03 -0700 (PDT)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Mon, 17 Oct 2011 Volume: 11 Number: 3522
Today's topics:
Re: help with pipe <jwkrahn@example.com>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Sun, 16 Oct 2011 15:09:12 -0700
From: "John W. Krahn" <jwkrahn@example.com>
Subject: Re: help with pipe
Message-Id: <dCImq.927$a23.685@newsfe18.iad>
bjlockie wrote:
>
> my $cmd = 'ping google.ca |';
>
> open( ZAP, $cmd ) || die "can't fork: $!";
>
> print $cmd . "\n";
>
> print "here2\n";
>
> my $numLines = 0;
>
> while (($numLines< 10)&& (my $line =<ZAP>)) {
> print $line;
> $numLines++;
> }
>
> print "here3\n";
>
>
> That doesn't exit the while loop and it prints the ping output to the
> screen.
Don't do it like that. You are not testing whether the value returned
from readline is defined. A better way would be:
my @cmd = qw/ ping google.ca /;
open my $ZAP, '-|', @cmd or die "Cannot open pipe from '@cmd' because: $!";
print "@cmd\n";
print "here2\n";
while ( my $line = <$ZAP> ) {
last if $. == 10;
print $line;
}
close $ZAP or warn $! ? "Error closing '@cmd' pipe: $!"
: "Exit status $? from '@cmd'";
print "here3\n";
__END__
John
--
Any intelligent fool can make things bigger and
more complex... It takes a touch of genius -
and a lot of courage to move in the opposite
direction. -- Albert Einstein
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
From: Perl-Users-Request@ruby.oce.orst.edu (Perl-Users-Digest Admin)
Subject: Digest Administrivia (Last modified: 6 Apr 01)
Message-Id: <null>
Administrivia:
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End of Perl-Users Digest V11 Issue 3522
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