In LINUX, what would the commands be for the following questions?:

1. The program ls(1) lists the contents of a directory. But it does not list any files whose names begin with . (period). What option would I give to ls to include those files in the output?

2. Every directory contains a subdirectory named ... What is that subdirectory? And what is the .. in the root directory /?

3. The file /usr/share/dict/words contains a list of English words. Write a command that will put all words in that file that contain the character sequence gry in the file GRY.

4. How would I list all files that begin with a and end with .txt?