SHIFT+F9 Gives MS-DOS Prompt, "Command Prompt" Item Disabled (78847)

The information in this article applies to:
    Microsoft MS-DOS operating system 5.0
    Microsoft MS-DOS operating system 5.0a
    Microsoft MS-DOS operating system 6.0

This article was previously published under Q78847


MS-DOS version 5.0 or later Shell allows you to access the command prompt several ways without exiting Shell. For example, you can:
    Execute the Command Prompt item in the main group.
    Use the SHIFT+F9 key combination.
    Highlight COMMAND.COM in the file list and press ENTER (or just double-click on the file with a mouse)
If pressing SHIFT+F9 shells to a command prompt but the Command Prompt item doesn't work, either change the entry in the Program Item Properties Commands text box from COMMAND to %COMSPEC%, or use the full drive, path, and filename of COMMAND.COM in the Commands text box.


In Shell, SHIFT+F9 runs the copy of COMMAND.COM referenced by the COMSPEC environment variable. This variable is set when loading the initial copy of COMMAND.COM on bootup. If the Command Prompt item is changed to run %COMSPEC% instead of COMMAND, the Command Prompt item will also execute the COMMAND.COM referenced by COMSPEC.

By default, the Commands text box in the Program Item Properties dialog box for the Command Prompt item is a single word: COMMAND. When the item is executed, the word gets changed to "@command", and placed into a batch file that is then run. If multiple releases of COMMAND.COM exist on the disk, the COMMAND.COM file accessed may be a non MS-DOS 5.0 release and therefore unusable. If COMMAND.COM is not in a directory included in the PATH environment variable, a COMMAND.COM file may not be found.

Periodically, COMMAND.COM needs to be reloaded into memory. MS-DOS uses the COMSPEC variable to determine where to reload COMMAND.COM. For more information on this process, see the section titled "Transient and resident memory" on page 385 of the version 5.0 "Microsoft MS-DOS 5.0 User's Guide and Reference."

Modification Type: Major Last Reviewed: 10/13/2003
Keywords: KB78847