AutoCAD's Support File Search Path

Since at least R14, inside the OPTIONS dialog, on the Files tab, the first expandable checkbox contains the Support File Search Path (SFSP).

This is a list of local and/or network paths in which AutoCAD looks for support files when needed. You might not put too much thought into this, and the settings on your machine may even be set by your CAD manager. But it's good to know how this affects AutoCAD.

Open up your AutoCAD to a blank drawing, run the -INSERT command, then type in some nonsense for the block name to insert, then press ENTER. You should get a message that lists the nonsense you typed in with a .DWG extension, and a list of the directories that were searched. This list will start out with the current directory, then the drawing directory, then a list of directories in the SFSP, in order from top to bottom.

The order is important in case there are duplicate file names in different directories. If you have a block in the current directory named "NET" and a block in another directory in the SFSP named "NET", the one in the current directory will be inserted unless you specify the full path

The SFSP order doesn't only affect inserting blocks. Startup files such as "acad.lsp", "acaddoc.lsp", and "acad.rx" are searched for in the same order as above. The first one found is the only one loaded. This can be useful if you are working on a set of drawings for a project that require some special lisp routines, or other customization. In this case, you can place startup files, blocks, and other support files in the drawing directory - which is searched before the SFSP.

Even the most basic plan for customizing AutoCAD can generally be accomplished by putting all your custom files in a single directory and then adding this directory to the TOP of your SFSP. When you do this, you don't have to worry about replacing or editing any Autodesk supplied files (like "Acad.pgp") - because yours will be loaded instead of the Autodesk file.

How do you use the SFSP search order to your advantage?