It's possible to create files and folders named CON and other reserved names from the command line. But first ...
Device names internal to MS-DOS and Windows include CON, AUX, PRN, CLOCK$, COM1, COM2, COM3, COM4, LPT1, LPT2, and LPT3. Because they exist as device names, they cannot usually be used as file and folder names.
This can lead to unusual problems. First, some background.
MS-DOS didn't include drivers for CD or DVD drives, even though it shipped with the CD file system extension. One can easily install a 3rd-party driver to provide CD support, however, and there are a couple of dozen such drivers around.
A few af the drivers set the CD-ROM driver to a predefined name like OEMCD001, but most allow the user to specify the name.
For instance, Microsoft used "MSCD001" for the CD drive name in the Windows 98 emergency boot disk. When the CD driver was NOT installed, you could create a file or folder named MSCD001 — when the driver WAS installed, MSCD001 could NOT be used, or if it existed, couldn't be opened.
"MSCD001", being an installed device name, automatically became a "reserved" name.
Now, an "unusual problem".
Some years ago, a friend found he couldn't install XP by booting from the CD drive. So, he acquired a boot floppy from bootdisk.com that included CD drive support. He booted from the CD and drive support loaded. He inserted the XP CD and ran winnt.exe on the CD to begin installation.
Which stopped with a file copy error about 15 minutes in. There was the usual message about a possibly scratched or dirty CD, or possibly a CD drive problem. So he cleaned and polished that disc until it shone — and the error persisted.
So he quit installation and restarted it, then watched it stop with the same error copying the same file. He called for advice and, when I learned the file name ("banana" something), I told him it was an insignificant file that he could skip — which he did, and got a good install.
We got together later and tried to find the cause of the copy error, but there was nothing. We finally considered that the boot floppy might be bad in some way, but it tested OK.
Booting from the floppy, a pretty slow process, and watching the screen, we were startled to see the word "BANANA" appear — twice.
Whoever prepared the boot floppy for download apparently felt "MSCD001" didn't cut it. So, he changed the CD driver names to BANANA — and in the process made it mysteriously impossible for that file be copied.
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To create a folder named CON, first open a Run prompt. To do this, tap the R key while pressing the Windows key (usually labeled "Start" or with the Microsoft flag).
Next, type CMD (or COMMAND if you're running 95, 98, or ME) and click OK to open a command prompt.
To create a folder named CON, type
MD CON\
and press Enter. Note the backslash following CON. To delete the folder, type
RD CON\
You can include a path, of course, using quotes if a space is present.
MD D:\Here\CON\
MD "D:\Still Here\CON\"
RD "D:\Still Here\CON\"
Creating a file named CON is trickier. Type
Echo This is the CON file> \\.\C:\CON
and press Enter. This creates a the CON file that consists of the line "This is the CON file".
To open the file, type Notepad \\.\C:\CON and press Enter. You can edit just as any text file, and resave it by clicking File and Save (or File, Exit, and Yes). Save As won't work, though.
You can create the file on other drives or in a folder,.
Echo This is the CON file> \\.\D:\There\CON
creates a CON file in the There folder on the D drive. If the path contains spaces, use quotes.
Echo This is the CON file> "\\.\D:\Over There\CON"
To delete and rename —
Del \\.\C:\CON
Ren \\.\C:\CON NotCON
Ren \\.\C:\CON "Not CON"
Del "\\.\D:\Over There\CON"
Ren "\\.\D:\Over There\CON" NotCON
Ren "\\.\D:\Over There\CON" "Not CON"