Probably historical preference for portability without a bunch of #ifdef means platform+version-specific stuff is very late to get adopted. Though, at this point, the benefit of portability across various posixy platforms is much lower.

io_uring is the asynchronous interface and that requires to use even-based architecture to use it effectively. But many command-line tools are still written is a straightforward sequential style. If C would have async or similar mechanism to pretend doing async programming sequentially, it would be easier to port. But without that a very significant refactoring is necessary.

Besides, io_uring is not yet stable and who knows may be in 10 years it will be replaced by yet another mechanism to take advantage of even newer hardware. So simply waiting for io_uring prove it is here to stay is very viable strategy. Besides in 10 years we may have tools/AI that will do the rewrite automatically...

iirc io_uring also had some pretty significant security issues early on (a couple of years ago). Those should be fixed by now, but that probably dampened adoption as well.

io_uring is a security nightmare.

> I'm trying to understand why all command line tools don't use io_uring.

Because it's fairly new. The coreutils package which contains the ls command (and the three earlier packages which were merged to create it) is decades old; io_uring appeared much later. It will take time for the "shared ring buffer" style of system call to win over traditional synchronous system calls.

One reason is so that they work in all linux environments rather than just bleeding edge installs from the last couple years.

Thats a great speed boost. What tools are these?

Iouring is very recent

Poe's law hits again.