The tuples historically had 3 components--cpu, vendor and operating system. But especially as uclibc and musl became more widespread the last component is commonly split into kernel-libc. (I think this was originally extended for the benefit of Debian GNU/kFreeBSD.) The formal OS identifier for glibc-based Linux systems is "linux-gnu" (e.g. x86_64-pc-linux-gnu), and for musl "linux-musl" (e.g. aarch64-alpine-linux-musl).
Vendor is not very useful these days. It's common to see 3-tuples of cpu-kernel-libc, as opposed to 4-tuples or traditional 3-tuples. Sometimes the system is extended into, e.g., 5-tuples like cpu-vendor-kernel-libc-compiler. Autotools projects commonly have a bit of generated shell code for parsing tuples; it's quite complex owing to ~30 years of accumulated idiosyncrasies.
The tuples historically had 3 components--cpu, vendor and operating system. But especially as uclibc and musl became more widespread the last component is commonly split into kernel-libc. (I think this was originally extended for the benefit of Debian GNU/kFreeBSD.) The formal OS identifier for glibc-based Linux systems is "linux-gnu" (e.g. x86_64-pc-linux-gnu), and for musl "linux-musl" (e.g. aarch64-alpine-linux-musl).
Vendor is not very useful these days. It's common to see 3-tuples of cpu-kernel-libc, as opposed to 4-tuples or traditional 3-tuples. Sometimes the system is extended into, e.g., 5-tuples like cpu-vendor-kernel-libc-compiler. Autotools projects commonly have a bit of generated shell code for parsing tuples; it's quite complex owing to ~30 years of accumulated idiosyncrasies.