IN THIS CHAPTER
System variables are the settings that AutoCAD checks before it decides how to do something. For example, if you leave the system variable SAVETIME at its default value of 10, AutoCAD saves the drawing file automatically every ten minutes; if you change SAVETIME to 60, the time between automatic saves is 1 hour. Hundreds of system variables control AutoCAD’s operations.
Most system variables are controlled by the OPtions command, but you can also change the value of a system variable by simply typing its name at the AutoCAD command prompt and pressing Enter. AutoCAD displays the current value of the system variable setting and prompts you for a new value. Press Enter to confirm the existing setting, or type a value and press Enter to change it.
This list describes the three kinds of system variables in AutoCAD and what happens when you change them: