File outFile = new File("/tmp/filelock.tmp");
FileOutputStream outputStream = new FileOutputStream(outFile);
FileChannel channel = outputStream.getChannel();
FileLock lock = channel.lock();
System.out.println("lock success");
lock.release();
channel.close();
outFile.delete();

#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>

int main() {

  int fd = open("/tmp/filelock.tmp", O_WRONLY);
  if (0 > fd) {
    printf("open file error, %s\n", strerror(errno));
    return errno;
  }
  struct flock the_lock;
  memset(&the_lock, 0, sizeof(struct flock));
  the_lock.l_type = F_WRLCK;
  the_lock.l_whence = SEEK_SET;
  the_lock.l_start = 0;
  the_lock.l_len = 0;

  if (-1 != fcntl(fd, F_SETLKW, &the_lock)) {
    printf("lock success \n");
    sleep(30);
    printf("sleep done\n");

    memset(&the_lock, 0, sizeof(struct flock));
    the_lock.l_type = F_UNLCK;
    the_lock.l_whence = SEEK_SET;
    the_lock.l_start = 0;
    the_lock.l_len = 0;
    if (0 == fcntl(fd, F_SETLKW, &the_lock)) {
      printf("unlock success \n");
    } else {
      printf("unlock error \n");

    }

  } else {
      printf("lock error %s\n", strerror(errno));

  }
  close(fd);
}