What is low-level or system programming?

C is considered a low-level or system programming language. If a C library were a duck, this is what you can do with a duck:

#include <dlfcn.h>

void* library = dlopen("./duck.so", RTLD_LAZY); typedef void (*duck_t)(); duck_t hello = (duck_t) dlsym(library, "walk"); walk();

Since you could create duck.so in Pascal, C++ or D, they can also be used effectively as system programming languages.

Java nor C# can walk like a duck, not even if that is what it would take to save themselves from drowning. The Go language cannot do this either.

For a language to be considered a valid substitute for C, it must simply be capable of walking like a duck. What other system programming languages are there around? What other languages are capable of walking like a duck?