Special Edition Using MS-DOS® 6.22, Third Edition

Appendix B. DOS Environment Variables

In this appendix

• Understanding the DOS Environment

• APPEND

• COMSPEC

• CONFIG

• COPYCMD

• DIRCMD

• MSDOSDATA

• PATH

• PROMPT

• TEMP and TMP

• windir

• WINPMT

Understanding the DOS Environment

The environment is a small area in memory that DOS sets aside for storing text variables. Normally, you set the size of the master environment area with a SHELL = statement in your CONFIG.SYS file. The default size of the environment is 256 bytes, but you almost certainly want to increase this size as you begin to use environment variables to automate your daily tasks.

Each variable in the environment consists of two parts: the name of the variable, which DOS stores in uppercase characters, and the contents of the variable, which is the text associated ...