How do I set the line end style without changing or edit in ctb or stb? 
If line has lineweight, it gets a rounded end. If I want to have a clean break at the end point, I need to set butt end style in ctb file.But Here My question is How do I set the line end style without toutch plot style? balboa2020-01-10 08:47:09

This is one way.  At the command line type STYLESMANAGER.  Choose the style you plot with.  Click on FORM VIEW.  Select ALL the objects in PLOT STYLES.  Now look for LINE END STYLE and change it to what you want.