Ho fedora core 1, ecco l'output

$ gcc Lnx.c
In file included from Lnx.c:21:
/usr/include/asm/io.h:4:2: warning: #warning <asm/io.h> is deprecated, use <sys/io.h> instead
Lnx.c: In function `main':
Lnx.c:110: warning: return type of `main' is not `int'
/tmp/ccEwZrLA.o(.text+0x64): In function `main':
: undefined reference to `kbhit'
collect2: ld returned 1 exit status