[Kobaz]

I've hit this in my "trying to learn C++ adventure". The *_s functions are Microsoft only. For sprintf_s you might try the POSIX snprintf:

int snprintf(char *str, size_t size, const char *format, ...);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       snprintf(), vsnprintf(): _BSD_SOURCE || _XOPEN_SOURCE >= 500 ||
       _ISOC99_SOURCE; or cc -std=c99

 The  functions  snprintf()  and  vsnprintf()  write  at most size bytes
       (including the trailing null byte ('\0')) to str.

This is from the man pages with glibc version 2.2