If you want to force vim to always automatically wrap lines when it hits the 80 character mark, I would suggest doing the following:
First, edit your vim resource file:
Next, set the option for textwidth to the number of characters limit:
Here's an alternative shorthand version of the textwidth option:
Last, set the option for formatoptions:
Here's an alternative shorthand version of the formatoptions option:
For more UNIX tips, please check out
Learning the UNIX Command Line.