I'm confused with C libraries
c, gnu, linux, standard-library
Solution
For the first question, glibc follows both standard C and POSIX, from About glibc
The GNU C Library is primarily designed to be a portable and high performance C library. It follows all relevant standards including ISO C11 and POSIX.1-2008. It is also internationalized and has one of the most complete internationalization interfaces known.
For the second question, yes, you can compile Linux using gcc. Even gcc itself can be compiled using gcc, it's called bootstrapping.
Problem
Ok here's the thing. Most people learn about the C standard library simultaneously as they first get in contact with the C language and I wasn't an exception either. But as I am studying linux now, I tend to get confused with C libraries. well first, I know that you get a nice old C standard lib as you install gcc on your linux distro as a static lib. After that, you get a new stable version of glibc pretty soon as you connect to the internet. I started to look into glibc API and here's where I got messed up. glibc seems to support vast amount of lib basically starting from POSIX C Standard lib (which implements the standard C lib(including C99 as I know of)) to it's own extensions based on the POSIX standard C lib. Does this mean that glibc actually modified or added functions in the POSIX C Standard lib? or even add whole new header set? Cause I see some functions that are not in the standard C lib but actually included in the standard C header (such as strnlen() in Also referring to what I mentioned about a 'glibc making whole new header set', is because I'm starting to see some header files that seems pretty unique such as linux/blahblah.h or sys/syscalls.h <= (are these the libs that only glibc support?) Next Ques is that I actually heard linux is built based on C language. Does this mean linux compiles itself with it's own gcc compiler???????