Watching files for changes

The moral of the story is, if you want to watch a file for changes, don't just listen to the Changed event on a FileSystemWatcher.

Different applications save files in different ways. Some just overwrite the original file, in which case Changed fires. Others attempt to create a two-phase commit transaction, so either the changes get saved or your original file is preserved (in case of a power outage). However depending on how they do this, they might never raise a Changed event against the file you're looking for - they might (for example) do all the changes to a temp file, then rename it.

Watching C:\*.* with a FileWatcherTestUI.NonBufferedFileSystemWatcher and updating a file 'UpdateSql.txt':

Notepad
[2006-07-10T10:45:27.1245966+08:00] Changed: C:\UpdateSQL.txt
[2006-07-10T10:45:27.1402217+08:00] Changed: C:\UpdateSQL.txt
[2006-07-10T10:45:27.2183472+08:00] Changed: C:\UpdateSQL.txt
 
VS 2003
[2006-07-10T10:45:17.3432840+08:00] Created: C:\ve-329.tmp
[2006-07-10T10:45:17.3589091+08:00] Changed: C:\ve-329.tmp
[2006-07-10T10:45:17.3589091+08:00] Changed: C:\ve-329.tmp
[2006-07-10T10:45:17.3589091+08:00] Changed: C:\ve-329.tmp
[2006-07-10T10:45:17.3745342+08:00] Changed: C:\UpdateSQL.txt
[2006-07-10T10:45:17.4214095+08:00] Changed: C:\UpdateSQL.txt
[2006-07-10T10:45:17.4526597+08:00] Changed: C:\UpdateSQL.txt
[2006-07-10T10:45:17.4682848+08:00] Deleted: C:\ve-329.tmp
 
VS 2005
[2006-07-10T10:45:37.3277869+08:00] Created: C:\ve-32B.tmp
[2006-07-10T10:45:37.3277869+08:00] Changed: C:\ve-32B.tmp
[2006-07-10T10:45:37.3434120+08:00] Changed: C:\ve-32B.tmp
[2006-07-10T10:45:37.3902873+08:00] Changed: C:\ve-32B.tmp
[2006-07-10T10:45:37.4371626+08:00] Changed: C:\ve-32B.tmp
[2006-07-10T10:45:37.4527877+08:00] Created: C:\UpdateSQL.txt~RFf7eb451.TMP
[2006-07-10T10:45:37.4684128+08:00] Deleted: C:\UpdateSQL.txt
[2006-07-10T10:45:37.4684128+08:00] Changed: C:\UpdateSQL.txt~RFf7eb451.TMP
[2006-07-10T10:45:37.4840379+08:00] Renamed: C:\UpdateSQL.txt (from ve-32B.tmp)
[2006-07-10T10:45:37.4996630+08:00] Deleted: C:\UpdateSQL.txt~RFf7eb451.TMP