ASSOCIATE.exe (NT/2000 Resource Kit)

One step file association.

This utility does the job of both ASSOC and FTYPE, in one step. ASSOCIATE assigns an extension directly with an executable application. This is done by automatically adding a new FileType to the system registry.

Syntax
      ASSOCIATE .ext filename [/q /d /f]

Key
   .ext     : Extension to be associated.
   filename : Executable program to associate .ext with.
   /q       : Quiet - Suppress interactive prompts.
   /f       : Force - Force overwrite or delete without questions.
   /d       : Delete - Delete the association.

A file extension is the last few characters in a FileName after the period.
So a file called JANUARY.HTML has the file extension .HTML

The File extension is used by Windows NT to determine the type of information stored in the file and therefore which application(s) will be able to display the information in the file. File extensions are not case sensitive and are not limited to 3 characters.

Example: adding a File Association

To add the File Type "SQLfile"=Notepad.exe and also set the File Association of .SQL="SQLfile" run this command:

ASSOCIATE .SQL Notepad.exe

This is equivalent to the two commands

FTYPE sqlfile="C:\Program Files\Syatem32\notepad.exe" "%1"
ASSOC .sql=sqlfile

Example: Removing a File Association

ASSOCIATE .SQL /d

Note that /d will delete the File Association but will NOT delete the File Type. You can achive the same with the standard command:

ASSOC .SQL=

File types created by Associate.exe are always given a name in the form xxxfile, where xxx is the file extension.

“The earth does not belong to man.... man belongs to the earth” ~ Chief Seattle

Related:

ASSOC - Change file extension associations.
FTYPE - Display or modify file types used in file extension associations.