bugfix:解决部分情况下颜色无法恢复默认的问题
new:section 8.2 Low Level I/O - Read and Write
new:section 8.3 Open, Creat, Close, Unlink
new:Exercise 8-1. Rewrite the program cat from Chapter 7 using read, write, open, and close
instead of their standard library equivalents. Perform experiments to determine the relative
speeds of the two versions.
improved:for exercise 8.1
changes: