... However, init, like almost all programs, uses functions from libraries. ... It comes from the standard C libraries, on a GNU/Linux system, glibc. ... They are libraries of these functions. ... There are two ways programs can use these library functions. ... For example, here are the libraries that bash uses: . ... Use ldd to find out what libraries init uses. ... Write, compile and link a program that uses this library. source code, see Building a Minimal Linux System from Source Code for urls . ...