Step $1$

Write a shell script that prompts the user to enter a valid directory.

If the input value is a valid directory then display a list of subdirectories in the given directory.

Else, display an appropriate error message.

Step $2$

Write a shell script that prompts the user to enter a valid directory.

$\backslash (\backslash$square $\backslash )$ Prompt the user to enter a valid directory as long as the input is invalid

$-$ If the input value is a valid directory then display a list of subdirectories in the given directory.

Step $3$

Write a shell script that prompts the user to enter a valid directory.

If the input value is a valid directory then display a list of files in the given directory.

Else, display an appropriate error message.

Step $4$

Write a shell script that prompts the user to enter a valid directory.

If the input value is a valid directory then do the following for each item in the given directory:

$-$ If the item is a directory then display a list of subdirectories in the given directory.

$-$ If the item is a file then display its name and size.

Else, display an appropriate error message.