Terminal: How to list current directory while typing out a path

I'm not sure how to phrase this correctly but I want to know how in the terminal to do the equivalent of 'ls' when typing out a path.

So for example i'm typing in:

sudo "/Library/Application Support/

Now i get stuck, i know if i could see inside 'Application Support' I would know where to go next. However i don't know how to get it out. So i resort to opening a second terminal doing something like 'ls /Library/Application Support/' or opening finder and looking in the folder for file/folder i'm looking for.

Is there a way to quickly type a command that will show the contents of where i'm at and leave my current command on screen so I don't need to retype it?

An answer for both Mac & Linux would be appreciated.