首先在linux下打开一个文件，然后将该文件上写入锁，并写入hello字符串。接着在解锁后再将该文件上读取锁，并读取刚才写好的内容。最后模拟多进程，同时读写一个文件时的情况。-First, open a file under linux, and then write lock on the file and write the string hello. Then, after unlocking the file lock on the read and write just to read the content. Finally, multi-process simulation, at the same time to read and write a paper on the circumstances.