Item — HN Reader

Author explained that by default if two files are the same size, and have the same modification date/time, that rsync will assume they're identical, WITHOUT CHECKING THAT.

Author clarifies there are flags to change that behaviour, to make it actually compare file contents, and then shares those names.

It seems like you didn't read the article.

3 comments

Short of checking every single byte against each other you need to do some sort of short hand.

“Assume these two files are the same, check if they either system is saying they have modified it or check if the size has changed and call it a day” is pretty fair of an assumption and something even I knew RSync is doing and I’ve only used it once in a project 10 years ago. I am sure Rachel also knows this.

So, what is the problem? Is data not being synced? Is data being synced too often? And why do these assumptions lead to either happening? What horrors is the author expecting the reader to see when running the suggested command?

That is what is not explained in the article.

Genuinely that's a feature not a bug. If you didn't rt"friendly"m the problem explicitly exists between keyboard/vr-headset and chair/standing-desk.

This should never be a surprise to people unless this is their first time using Unix.

They also have to have the same name though. The actual chances of this situation happening and persisting long enough to matter are pretty damn small.