Jakub Narebski <jnareb@xxxxxxxxx> writes:
> Jeff King wrote:
>
>> On Wed, Oct 11, 2006 at 02:23:00PM +0200, Jakub Narebski wrote:
>>
>>> Can any Perl expert tell us how Perl truly solve this? What is the best
>>> way to dump whole [remaining] contents of file (from filehandle) to STDOUT?
>>
>> The same you would in C: read fix-sized buffers and dump them.
> [...]
>> Or you can use the File::Copy module, which is part of the standard
>> distribution (and I believe has been so for all perl5 versions, but I
>> could be wrong):
>
> And
>
> {
> local $/;
> print <$fd>;
> }
>
> doesn't do the right thing?
Jakub, you asked for "the best way" not "any way that would
produce a correct result". Your 4-liner is shorter in the
source but it risks slurping a 10 megabyte file into memory
first, only to discard it after immediately writing it out.
You can strace your Perl to see what yours does yourself:
strace perl -e 'print <STDIN>' >/dev/null <some-huge-file
You will see a bunch of read(0, ..., 4096) and after all of that
finishes, finally you will see a bunch of write(1, ..., 4096).
Where do you think the data is in the meantime?
Jeff gave you better ways that do not have that problem.
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