Command Piped in Root Directory May Hang Machine (82216)

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
    Microsoft MS-DOS operating system 6.2
    Microsoft MS-DOS operating system 6.21
    Microsoft MS-DOS operating system 6.22
    Microsoft Windows 3.0
    Microsoft Windows 3.0a
    Microsoft Windows 3.1
    Microsoft Windows 3.11

This article was previously published under Q82216


If you run an MS-DOS command in a root directory that contains the maximum allowable number of directory entries, and redirect the output by using a pipe character (|), your system may stop responding (hang).


MS-DOS provides the means to direct the output of one command as input to another using a redirection technique known as "piping." Because MS-DOS is a single-tasking environment, these pipes are created via temporary files on disk.

MS-DOS checks for the presence of an environment variable called TEMP specifying the drive and directory where such temporary files should be placed. If no TEMP variable or directory exists, MS-DOS uses the current directory.

If the output from one command is piped to another when the current directory is a root directory that already contains the maximum number of directory entries (for example, 512 files for fixed disks,) the inability to create the temporary files may stop (hang) the machine.


To eliminate this problem, do the following:
    Delete or move some files from the root directory to create space for additional directory entries. -or-

    Create an X:\TEMP directory and place a SET TEMP=X:\TEMP statement in the AUTOEXEC.BAT file. The temporary files created by the pipe are then placed in the X:\TEMP directory, where X: is a valid MS-DOS logical drive.


Microsoft has confirmed this to be a problem in MS-DOS. We are researching this problem and will post new information here as it becomes available.


For additional information on command redirection, refer to the "Microsoft MS-DOS User's Guide and Reference," for version 5.0.

For additional information on the limits of the root directory with regard to the number of directory entries, query on the following words in the Microsoft Knowledge Base:

directory and limit and entries

Modification Type: Major Last Reviewed: 5/12/2003
Keywords: KB82216