This might have some to do with the /home/[your-user-name]/.bashrc file.
Check for that file, if it is not existing at all copy it from /etc/skel/.bashrc using
sudo cp /etc/skel/.bashrc /home/[your-user-name]/.
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