Can anyone tell me why the the following does not work as an example of a mutex under Linux 

```
#include <pthread.h>
int main (){
pthread_mutex_t start;
if (pthread_mutex_init(&start, NULL) != 0){
     printf("err!");
     return(1);
}
if (pthread_mutex_lock(&start) != 0){
     printf("err!");
     return(1);
}

pthread_mutex_unlock(&start);
pthread_mutex_destroy(&start);
}

```