> relies on sys-calls No, the rely on POSIX[1][2]. Syscalls are an implementation detail handled by the compiler. Programs (like 'ls' and the rest of coreutils

> relies on sys-calls No, the rely on POSIX[1][2]. Syscalls are an implementation detail handled by the compiler. Programs (like 'ls' and the rest of coreutils) that conform[3] to the POSIX standard should continue to work in future POSIX compatible operating systems. If future operating systems deliberately introduce changes that break POSIX, then some work will be required to port the programs to the new environment. However, this type of porting process is really implementing a new feature. The original finished version isn't affected and shouldn't need maintenance. [1] https://en.wikipedia.org/wiki/POSIX https://en.wikipedia.org/wiki/POSIX [2] Other standards are also important, but I am only mentioning POSIX for brevity. [3] https://github.com/coreutils/coreutils https://github.com/coreutils/coreutils "Like the rest of the GNU system, these programs mostly conform to POSIX, with BSD and other extensions."