Set Paths is a control panel file which maintains a list of up to five folders. Once Set Paths has been used, that list will be used as a search path any time a file open operation occurs. If the file is not found where the programmer told the system to look, the system will start searching your list of folders and will fail to find the file only if it is in none of them.
The main purpose of Set Paths is to help reduce System Folder clutter, most specifically System Folders filled with jillions of laser fonts. However, many other things that normally go into your System Folder cannot be placed anywhere else. It can also make life easier for developers who have source files, object files, compilers, linkers, and editors littered all over their disks.
Using Set Paths is simple. Bring up the Control Panel desk accessory and scroll down to and click on "Set Paths". There are three buttons, a check box, and a box which displays the current list of folder names.
The "Add…" button will add a new folder to the list. Clicking on it brings up an open dialog. Find the folder that you wish to add to the list and click on the "Select" button.
To delete folders from the list, click on their names (in the Control Panel window, not the Finder) and click on the "Delete" button.
When "Show icon during startup" is clicked, the Set Paths icon will show at the bottom of your screen when it loads during startup of your Mac.
Set Paths is totally transparent to the system. Once you've set your paths, you're running - no matter what application you happen to be using. And you can use Set Paths any time you'd like to change your search path list. If you want to turn it off, you'll have to take it out of your System Folder or use a program like 'init cdev' to disable it (and then restart your Macintosh).
When you use Set Paths to select a folder on another disk, you must keep in mind a few things. Internally, each folder is stored as a pair of numbers which refer to the disk and the folder on the disk. The disk is referred to by something called the "volume reference number". This number is a unique number for referring to a disk, but the numbers are only unique at any one point in time. Once a disk is forgotten by the Mac, (such as by throwing it in the trash in the Finder) the number is up for grabs again. Unless you are using a Mac without hard disk, your startup disk usually has the same number.
First, if you set a path to a folder on a disk other than your startup disk, and it is not online, the folder name in Set Paths will be replaced with "*Unmounted volume*". This is not a problem.
Second, if you throw this disk's icon away and then insert another disk, you might get a folder on the other disk instead. This is because each disk has a unique (and non-reused) ID number for every folder on the disk. However, different disks may have folders with the same ID number, and you'll unexpectedly get a folder from the wrong disk used instead. Even in this case, however, there probably won't be any problem. However, you might want to use a little caution with adding paths to folders on disks other than your startup disk.
Disclaimer: This control panel file uses completely undocumented technology. If Set Paths somehow messes up your hard disk or data files, I will not be responsible for any problems that arise as a result of the use of it. Always back up your hard disk. Have a nice day. Don't worry, be happy. But don't take this disclaimer to indicate that Set Paths is a completely unstable hard disk trasher. It's just that it makes an undocumented system call, and the only guy who really understands it probably left Apple a couple of years back. The end result is that Set Paths merely adds other folders to a list that normally only refers to the System Folder.
The Set Paths control file is based on a desk accessory done by Paul Snively a few years back. A long time ago I suggested to him the idea of making it into a control panel file, but got a neutral response. It wasn't until I had to keep opening a System Folder with over 350 laser font files in it (takes a long time even on a IIx!) that the idea came back to me. Thanks to Paul's work in his Set Paths desk accessory, I was able to use the extensively undocumented _SetPMSP call.
