# file type.
so(linux.elf)  dll(windows). # dynamic library.
a(linux.elf) lib(windows). # static library.
out(liunx.elf) exe(windows.PE). # executable file.

# compile file type.
c,h --(precompile)--> i --(compile)--> asm(s,a,assembly) --(assembly)--> o --(link)--> out,a,so(executable).



# system console.
/dev/console

# terminal.
/dev/tty

# null device.
/dev/null