> Sure, but the article is talking about grep, not write() or libc implementations.

Yes, but you said

> In this case, the library that buffers in userspace should set appropriate timers when it first buffers the data

The library that buffers in userspace for grep and tcpdump is almost certainly libc.

Okay, I should have said “a” instead of using “the” when there is no clear antecedent allowing it to be interpreted ambiguously in exactly that single sentence which apparently invalidated the fact that I was obviously talking in generalities of API design and implementation.

It did not even occur to me that anybody would even think this was some sort of statement about whatever libc they use on Linux given that I said just “buffered accesses” with no reference to platform or transport channel.

I thought somebody might think I was talking about just writes, so I deliberately wrote accesses.

I thought somebody would make some sort of pedantic statement if I just said “should” so I wrote “should almost always”.

I thought somebody might think I was talking about write() in particular so I deliberately avoided talking about any specific API to head that off.

In my reply I deliberately said “blocking read/wait” instead of select() or epoll() or io_uring or whatever other thing they use these days to avoid such confusion that it was a specific remedy for a specific library or API.

But, alas, here we are. My pedantry was no match for first contact. You will just have to forgive my inability to consider the dire implications of minor ambiguities.