Before
DOS 5.01 and the inception of
edit.com (may have been
edit.exe, however I'm not willing to pull out an old DOS disk set and find out), it was nearly impossible to write or edit text files with the default DOS installation. There were utilites printed in magazines, and distributed on
diskettes that allowed for the manipulation of simple text files, but the only one that was included with DOS was
edlin, and those who have successfuly used this program hardly live to tell of it. So,
copy con was the way to go if you needed to edit
config.sys to get an extra 10k of upper memory free.
Unfortunately, when I say edit, I really mean delete the file and write a new one from scratch. So, many people just used copy con for the creation of files. True sadists first printed out the contents of the file with type filename.txt, then handcopied every previous line. Ouch. The correct (IIRC) method for copy coning a file goes as follows:
C:\>copy con rungolf.bat
cd\games\golf
golf.exe
^Z
1 file(s) copied
C:\>
In *nix, the same effect can be had with cat > file.txt, and any subsequent input after that statement, preceding a ctrl-c or ctrl-d, will be recorded in file.txt.
1. Sources tell me that DOS 3.0 included edit.com as one of the programs. So it may have been in previous versions of DOS where this was widely used. *shudder*.