Last Argument Of The Last Command

You can use !$ as a way to reference the last argument in the last command. This makes for an easy shortcut when you want to switch out commands for the same long file name. For instance, if you just ran cat on a file to see its contents

$ cat /Users/jbranchaud/.ssh/config

and now you want to edit that file. You can just pass !$ to the vim command:

$ vim !$

Hit enter or tab to get the full command:

$ vim /Users/jbranchaud/.ssh/config

h/t Dorian Karter