cp: Wrong handling of -i -u

[BenWiederhake]

When copying an old file over a new file, cp still needs to ask: -u is --update=older, which according to the man page only influences which files are considered for overwriting. In other words, -u does not work by automatically allowing anything, but rather by disregarding some copy actions.

Minimal example:

$ touch old; sleep 2; touch new; echo N | LC_ALL=C cp -i -u new old
cp: overwrite 'old'? [$? = 1]
$ touch old; sleep 2; touch new; echo N | cargo run cp -i -u new old
$

Found while trying to fix #4725.

[Vikrant2691]

I am ready to take this issue. please let me know..

[tertsdiepraam]

@Vikrant2691 I haven't verified this issue myself, but I trust @BenWiederhake :) Feel free to pick this up!

[BenWiederhake]

@Vikrant2691 I'm glad you're helping, yes, please do! :D

[Vikrant2691]

Thank you @BenWiederhake and @tertsdiepraam, I will try to replicate the issue at my end and check out! :)

[Vikrant2691]

I was able to replicate the issue

$ echo "hello">old; touch new
$ coreutils cp -i -u new old  # no prompt
$ cp -i -u new old
cp: overwrite 'old'? N

Additionally, coreutils is not overwriting the file.
I will look into this

[Vikrant2691]

Hi @BenWiederhake and @tertsdiepraam please let me know if the PR is ok to be merged or needs more work. :)

[BenWiederhake]

Closing, because #6069 was factually merged.