In this assignment you will write a recursive function in bash that will do a preorder traversal of a given directory and list the contents of the directory and all the sub$-$directories under it$.$ The behavior of your script should be similar to that of $\text{'}$ls $-$R arg$1\text{'}$ where arg$1$ is the directory that needs to be traversed and listed.

NOTE: You are not allowed to use $\text{'}$ls$\text{'}$ or any other command that displays the contents of a directory. You can use echo, pwd$,$ and cd$.$

There are empty directories and symbolic links, these should not be printed when using echo. These need to be set to dev$/$null or ignored in some other way.