MORE INFORMATION

There are some restrictions on this method of using PATH. Once you set the path in the CONFIG.SYS file, you cannot change it later. You cannot use the %PATH% variable to append the path onto itself or run another batch file to modify the path. If you do either of these, the path is truncated to the first 128 characters.

Also, some applications do not have the ability to use a long path. For example, the MS-DOS command SET does not display more than the first 128 characters of the path. To see the complete path, use the OS option of Microsoft Diagnostics (MSD.EXE). If you have problems using a third-party application and a long path, contact the manufacturer of the application for possible solutions.

Paths Longer Than 256 Characters

There is one problem with paths longer than 256 characters. If you clear the PATH variable with the SET command as follows any characters beyond the 256-limit appear in your environment space, unassociated with any environment variables. For example, if you have a path of 260 characters, such as and you clear it with the SET command, your environment space still contains the last four characters. If you type the SET command alone to view your environment, you see something similar to the following:

   work
   PROMPT=$P$G
   COMSPEC=C:\DOS\COMMAND.COM
   TEMP=C:\TEMP

Microsoft has confirmed this to be a problem in MS-DOS versions 6.0, 6.2, and 6.21. We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.

If the Path Is in the CONFIG.SYS File

If you place the path statement in the CONFIG.SYS file, you may need to manually update the path whenever you install a new program. Many software packages use a setup utility to install the program to the hard disk drive. Generally, these setup utilities modify the AUTOEXEC.BAT file by adding a directory name to the path statement. If the path statement is located in the CONFIG.SYS file, the setup utility cannot find it and creates a new path statement in the AUTOEXEC.BAT file. When the system is started, the path in the AUTOEXEC.BAT file replaces the path loading from the CONFIG.SYS file, leaving you with a path pointing to only one directory.

To work around this problem, each time you install a program, you must add the program's directory name to the path in the CONFIG.SYS file and erase the path line in the AUTOEXEC.BAT file.