Right, the standard centos system binaries are used to provision services and manage hardware.
The internal services linking against the runtime libs you mention, are actually linking against about 2000 built from source packages, and are essentially a separate distro (with a distro in this sense being an ABI compatible set of libs running on a kernel)
It's worth noting that this discusses the centos based provisioning and hardware management platform.
The actual distribution used to _run_ all Meta backend services is completely separate and built from source
(it does share the (non centos) kernel). This is done for flexibility, performance, service isolation reasons
All the main platforms have realpath(1). It was added to GNU Linux over 10 years ago now, to aid portability, and be a more natural command to access this functionality than readlink(1)
An interesting factoid is that FreeBSD/macos sort(1) was using GNU code until recently, since this is quite tricky to implement. Eventually it was reimplemented for GPL avoidance reasons.
We do consider macos though, and ensure all tests pass on macos for each release
https://discourse.ubuntu.com/t/an-update-on-rust-coreutils/8...