Re: Reading partial lines/strings from a pipe

When working with raw bytes, it pays to use the read method. It will block until something is available, then read up to a specified number of bytes:

# from Programming Perl
my $buffer;
while ( read $your_handle, $buffer, 1024 ) {
    # process buffer here
}
[download]

That will read up to 1K from the handle, blocking if nothing is there, but returning whatever is there (the first 1K of it anyway).

The Perl Cookbook is an excellent reference for doing this sort of work.

Phil

The Gantry Web Framework Book is now available.

Comment on Re: Reading partial lines/strings from a pipe Download Code

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Re^2: Reading partial lines/strings from a pipe by slightly72 (Initiate) on Oct 10, 2007 at 18:24 UTC
Phil, thank you very much for the pointer and the book reference, it got me in the right direction. The final solution is almost like the one you suggested: `my $buffer = ''; $rdr->blocking(0); while ($buffer eq '') { $rdr->read($buffer,1024); }` [download] $rdr->read is just an OO wrapper for read. The key to making this work was to use $rdr->blocking(0), which makes the pipe reading non-blocking. Otherwise a deadlock occurs -- maybe because the read command blocks while waiting for 1k to be filled, but not sure. Thank you, Tibi	[reply] [d/l]

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Re^2: Reading partial lines/strings from a pipe
by slightly72 (Initiate) on Oct 10, 2007 at 18:24 UTC

Phil, thank you very much for the pointer and the book reference, it got me in the right direction.

The final solution is almost like the one you suggested:

my $buffer = '';
$rdr->blocking(0);
while ($buffer eq '') {
    $rdr->read($buffer,1024);
}
[download]

$rdr->read is just an OO wrapper for read.

The key to making this work was to use $rdr->blocking(0), which makes the pipe reading non-blocking. Otherwise a deadlock occurs -- maybe because the read command blocks while waiting for 1k to be filled, but not sure.

Thank you,
Tibi

[reply]
[d/l]