rt-thread/components/libc/posix/readme.md

This folder provides functions that are not part of the standard C library but are part of the POSIX.1 (IEEE Standard 1003.1) standard.

NOTE

1. For consistency of compilation results across the different of platforms(gcc, keil, iar) , use:
   • #include <sys/time.h> to instead of #include <time.h>
   • #include <sys/errno.h> to instead of #include <errno.h>
   • #include <sys/signal.h> to instead of #include <signal.h>