B&O 9.14 (start with the source code in the solution for problem 9.5).
Be sure to print the contents of hello.txt to ensure you made the correct change.
Note that you can easily create the hello.txt file with:
$ echo "Hello, world!
" > hello.txt
Likewise you can print its content:
$ cat hello.txt
Question: What flags are needed on the mmap call to make the file change visible?
Copy/paste your source code solution here: