python 2.7.12 on Linux behaving differently than on Windows

Jon Ribbens jon+usenet at unequivocal.eu
Tue Dec 6 08:05:39 EST 2016


On 2016-12-06, Chris Angelico <rosuav at gmail.com> wrote:
> On Tue, Dec 6, 2016 at 10:56 PM, BartC <bc at freeuk.com> wrote:
>> In that directory (which was on Windows but accessible via a virtual Linux),
>> typing any Linux command followed by * would have required all 3.4 million
>> directory entries to be accessed in order to build a 3.4 million-element
>> argv list. I've no idea how long that would have taken.
>
> I just asked Python to build me a 4-million-element list, and it took
> no visible time - a small fraction of a second. Don't be afraid of
> large argument lists. We're not writing 8088 Assembly Language
> programs in 64KB of working memory here.

To be fair, literally just now I couldn't run the command I wanted to:

  sed -i -e 's/foo/bar/g' /dir/ectory/*.txt

because there were 300,000 files matching the glob, and 'sed' can't
cope with that many command-line arguments. I had to do this instead:

  find /dir/ectory -name '*.txt' -exec sed -i -e 's/foo/bar/g' {} \;

(Yes, I could also have done something with 'xargs' instead, which
would've been slower to write and quicker to run.)

However please don't take that to mean I agree with BartC - he's
clearly just reacting with instinctive hostility to the unknown.


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