Regular expression for file and directory listing

I guess ls is a laudable command in the Linux world – the fact that everything is a file, we exploit it in a daily manner.
One usage of the a helpful command on ls is grep for listing regex’d listing.
here is the the simplest command that can list all the files/directories with that start with ‘pe’
First we would be on the directory we want the listing, then we would pipe the listing to grep!

ls | grep "^pe.*"


ls | grep "^pe" 

would result the same.
One that contains pe would be

ls | grep "pe"

and the one that ends with pe would be

ls | grep "pe$"

Further reading Ubunutu help on grep