> The problem is not the lack of a standard, it is that Glibc does not follow the standard and is itself the de facto choice for desktop Linux. Applications tha

> The problem is not the lack of a standard, it is that Glibc does not follow the standard and is itself the de facto choice for desktop Linux. Applications that assume Glibc may not work on other implementations ( like MUSL ). That's incorrect Glibc does follow the relevant standards, you can simply restrict yourself to only use POSIX and C11, it's just that program authors find the glibc-extensions convenient enough to use them over just the bare standard. That said, some of the other libraries don't even claim to support the relevant standards, e.g. Bionic is not even fully POSIX compliant. So an application that assumes MUSL (which btw, also implements glibc, BSD and Linux extensions), can't use Bionic as a drop in replacement (not sure about Relibc).