lseek.c

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

int main(int argc, char **argv)
{
    int fd;
    int ret;

    if (argc != 2) {
        fprintf(stderr, "<%s> filename\n", argv[0]);
        return -1;
    }

    fd = open(argv[1], O_RDONLY);
    if (fd < 0) {
        return -1;
    }

    while (1) {
        char bytes[1000];

        ret = read(fd, bytes, sizeof(bytes));
        if (ret <= 0) {
            // reached eof .. set to beginning of the file
            lseek(fd, 0, SEEK_SET);

            fprintf(stderr, " reached EOF.. setting to the beginning of file\n");

            sleep(1);
        } else {
            write(2, bytes, ret);
        }
    }

    close(fd);

    return 0;
}