1. (Linux) the ls command has lots of options. What options or commands will:
   1. show nonprinting characters in octal
   2. list files by creation/modification time
   3. indicate file type by appending / to directories, * to executables and @ to symbolic links
   4. list only the directory name, not its contents
   5. list all files, even those normally hidden
   6. recursively list subdirectories as well as the current directory
   7. list files according to modification time
   8. show permissions, owner, size, modification type