some basics command in linux system. Answer the following 4 commands:

1 ) Write a command that will create the directory ~/cs140u/hw5

2 ) Write a command that will set the permission of the directory ~/cs140u/hw5 so that only the owner can read, write, and execute the directory. No other users should have read, write, or execute permission on the directory.

3 ) Write a command that will set the permission of the directory ~/cs140u so that no ordinary user can create or delete files in the directory.

4 ) Write a command that will allow user Alex.S , and no other user, to create and delete files in the ~/cs140u directory, without changing any ownership or group assignments you set in the previous question.