$DEFAULTDIR$ is assigned the value of the primary directory in which the installation occurs. This value includes both the disk drive and the directory path. Typically, the administrator assigns a suggested value using the DEFAULTDIR command and gives the user the option of changing it. The variable is assigned its value after the user has had a chance to change the value so that it accurately reflects where to install the files.

Common uses include:

  • Adding the installation directory to the user's PATH.
  • Adding a device driver to the Config.sys file.
  • Providing the installation directory path to an external executable.