When you use the vi editor and change environment settings at the : set number to enable line numbering, those changes are lost when you exit the vi editor. to continuously apply the same environment settings, you can choose to put the set commands in a special hidden file in their home directory called .exrc; this .exrc file is then applied each time you open the vi editor. enter the vi editor and find three environment settings that you want to change in addition to line numbering. then create a new file called .exrc in your home directory and enter the four lines changing these vi environment settings (do not start each line with a : character, just enter the set command – e.g., set number). when finished, open the vi editor to edit a new file and test to see whether the settings were applied automatically.