This is a hello world example on linux without using the C standard library or any dynamic libs.

freestanding.c

unsigned long int LinuxWrite(unsigned fd, const char *str, unsigned long len)
{
        unsigned long ret = -1;
        __asm__ __volatile__("int $0x80" : "=a" (ret) : "a" (4), "b" (fd), "c" (str), "d" (len));
        return ret;
}

void LinuxExit(int code)
{
        __asm__ __volatile__ ("int $0x80" :: "a" (1), "b" (code));
}

unsigned long strlen(const char *str)
{
        unsigned long len = 0;
        while (*str++)
                len++;
        return len;
}

static inline void LinuxPuts(const char *str) { LinuxWrite(1, str, strlen(str)); }

void _start(void)
{
        LinuxPuts("Hello World!\n");
        LinuxExit(0);
}