Question

The directory "a" contains its subdirectory "b" and there is no other entry in the directory "a". You want to display "the contents of directory a are: b". The contents are to be displayed using "ls" command. Which command helps you accomplish that?

Answer 1

The answer assumes that the question is about which command help accomplish display directory contents in Unix-like operating systems.

Answer:

The command is ls.

Explanation:

The command ls (short for list) displays a variety of important information in different ways regarding any directory contents. Because of this, it is probably one of the most used commands in Unix-like operating systems.

Any directory can contain directories and files of different sizes, recently created/modified, attributes like permissions for being accessed, and, with this command, we can see all this information by size, chronologically, by owner, and/or by many more ways.  

In the question, we can accomplish to list that the directory "a" contains its sub-directory "b" and no other entry using the next line of code:

Command-line 1: $\\ ls\; a$ (the command "says": display content of a)

Result: $b$

The result is only the directory b because there is no other entry in it.

To display more information regarding b, we can use the many options available for the command ls, like -a (all entries), -d (only directories), -l (long listing format), and so on, e.g. ls -a  A (display all entries in directory A, included hidden files).