The Linux "copy problem"

Posted May 30, 2019 16:00 UTC (Thu) by KAMiKAZOW (guest, #107958)
In reply to: The Linux "copy problem" by roc
Parent article: The Linux "copy problem"

> It seems like it would be worth at least diving into `cp` and making sure it's as good as can be, since that gets used so much.

I find it insane that cp was fixed a decade ago by NASA and in all that time neither them nor anybody else thought about upstreaming the changes.

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The Linux "copy problem"

Posted May 30, 2019 16:17 UTC (Thu) by desbma (guest, #118820) [Link] (4 responses)

Unfortunately, there are many other example of cases like this.

For example zlib, one the most widely used software library in the world, has several forks (Intel, Cloudflare, zlib-ng...) with optimizations that improve compression/decompression speed.

Yet the changes have never been merged back in zlib, and everybody still uses the historic version, and happily wastes CPU cycles (including when your browser decompresses this very page).

The Linux "copy problem"

Posted Jun 2, 2019 3:07 UTC (Sun) by scientes (guest, #83068) [Link] (3 responses)

> (including when your browser decompresses this very page).

Compression is disabled for https sites due to various attacks on the file size information leak.

The Linux "copy problem"

Posted Jun 2, 2019 10:27 UTC (Sun) by desbma (guest, #118820) [Link] (2 responses)

My browser (and curl) both disagree with you:
curl -v --compressed 'https://lwn.net/' > /dev/null 2>&1 | grep gzip
> Accept-Encoding: deflate, gzip
< Content-Encoding: gzip

The Linux "copy problem"

Posted Jun 2, 2019 12:20 UTC (Sun) by Jandar (subscriber, #85683) [Link] (1 responses)

> curl -v --compressed 'https://lwn.net/' > /dev/null 2>&1 | grep gzip

This command is obviously without any output.

$ curl -v --compressed 'https://lwn.net/' > /dev/null 2>&1 | wc
0 0 0

Perhaps you meant: curl -v --compressed 'https://lwn.net/' 2>&1 > /dev/null | grep gzip

The Linux "copy problem"

Posted Jun 2, 2019 12:45 UTC (Sun) by desbma (guest, #118820) [Link]

You are right, I'm using ZSH and didn't realize that line was not portable across other shells.

curl -v --compressed 'https://lwn.net/' -o /dev/null 2>&1 | grep gzip

also works