For users of Mac OS 9: The discussion on this page is relevant only if you are using Mac OS 9.
Determining whether a file is ever used by anything can be tricky. There are only three reliable indicators that something uses a preference file, and we have no guarantee that any of them will be true even if a file is used.
They are:
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The file is actually in use when File Buddy checks it. Some software leaves its preferences files open while it's running, but a lot don't, and most of your software is probably not running at the time of the scan anyway. |
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The file has been modified recently. While it might be the case the modification date was changed some other way, it's a pretty safe bet that if a file has been modified recently, something has opened it and made changes to it. However, it's possible a program opens the file, reads what it needs, and then closes it without making changes. |
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The file's creator signature belongs to something in the desktop database. There are two problems with this approach: |
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Some programs create their preference files with a creator signature other than their own. |
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The desktop database may not be current. If applications have been deleted since the last time the desktop database was rebuilt, orphaned files may mistakenly appear to be used. |
File Buddy can determine that some files are used, but it cannot determine with certainty that a file is obsolete. So it ignores files appears to belong to something according to the tests above, and those whose Finder labels have been selected to ignore. Everything else it reports as questionable. |
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Once the results of the scan are reported, it's your call to decide the fate of the questionable files. If you don't know whether a file is used or not, it's probably best to leave for the time being. You can always delete it later. |
Historical Note: At one time Apple recommended giving a preference file the creator '????' to prevent launching an application if you tried to open its preference file. |
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Apple has since recanted on this, in part so utilities such as File Buddy can do a better job of keeping the Preferences folder clean. |
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Tidbit: Officially, '????' is the creator of a non-existent application. During a desktop rebuild, applications with this creator are ignored, and hence the Finder can never find an application to open files with a creator signature of '????'. |