3.c

#include <stdio.h>
#include <string.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#include <unistd.h>

#define FILENAME "./test"

enum {
    BUFSIZE = 1024
};

int main(void)
{
    char buf[BUFSIZE] = { 0 };
    int ret;
    int fd;

    fd = open(FILENAME, O_RDONLY);
    printf("fd = %d\n", fd);

    ret = read(fd, buf, BUFSIZE);
    printf("ret = %d\n", ret);
    write(1, buf, strlen(buf));


    return 0;
}