[jdan222]

I am pretty sure you have to add it to the configuration file for line numbers to display each time you open a new file.

[ShinTakuya]

So the "rc" in vimrc means "run commands". And while the term gets abused, by and large what's in vimrc can just be run directly by yourself in vim without a file. All the config file really does is run a list of commands on startup.