How to check file format in Linux vi / vim editor

Purpose:

sometime user may run into situations that files cannot be properly recognized after our modifications.  When checking the difference on those modified files , we probably found lots of ^M in end of the lines. 

Most of these issues are from the format mismatched.  

System requirements:

• Not Hardware related , it's Linux Environments 

Target Audience:

• Advantechers technician.
• Customers

Steps

If the utility should import settings or configs from unix format , you may follow steps in below to change it in editor (vi or vim)

:set ff (check file format)
:set ff=unix (set file format to unix)
:set ff=dos (set file format to dos)