Even more: clone3, __clone2 (only exists on Itanium), fchmodat2, preadv2, pwritev2, pipe2, sync_file_range2, mmap2 (only certain architectures; for x86, only 32-bit), renameat2, mlock2, faccessat2, epoll_pwait2

My personal prediction is sooner or later we'll see execveat2, to permit setting /proc/PID/comm when using execveat [0].

I doubt we'll ever see clone4, because clone3 is passed a structure argument with the structure size, so new fields can be supported just by increasing the structure size. If other syscalls had done that from the start, much of the 2/3/etc would have been avoided. It is actually a very common practice on Windows (since NT), it has only much more recently been adopted in the Linux kernel

[0] see https://uapi-group.org/kernel-features/

I work on a team that supports some equipment related to airplanes. An acronym for one piece of equipment that is decades old is "RCSU". When I got a support call talking about "RSCU", I assumed the person meant "RCSU".

Nope. It turns out, when they made their next-generation piece of equipment, the vendor differentiated it by swapping the inner two letters in an already easy-to-say-wrong acronym.

My reaction was, "WTF didn't they just call it the RCSU2?!"