Filemon monitors and displays file system activity on a system in real-time. Its advanced capabilities make it a powerful tool for exploring the way Windows works, seeing how applications use the files and DLLs, or tracking down problems in system or application file configurations.

Filemon`s timestamping feature will show you precisely when every open, read, write or delete, happens, and its status column tells you the outcome.

Filemon is so easy to use that you`ll be an expert within minutes. It begins monitoring when you start it, and its output window can be saved to a file for off-line viewing. It has full search capability, and if you find that you`re getting information overload, simply set up one or more filters.

Filemon works on NT 4.0, Windows 2000, Windows XP, Windows XP 64-bit Edition, Windows 95, Windows 98 and Windows ME. Sysinternals also has a version of Filemon for Linux.

Installation and Use Simply run FileMon (filemon.exe). You must have administrator privilege to run FileMon. When FileMon is started for the first time it will monitor all local hard drives. Menus, hot-keys, or toolbar buttons can be used to clear the window, select and deselect monitored volumes including network volumes (Windows NT/2K/XP), save the monitored data to a file, and to filter and search output.

If you've specified filters then FileMon will ask you to confirm filters used from the last session each time you start it. To start FileMon without it prompting you specify the /q switch on the command line. When FileMon starts it automatically captures file system activity. To start it with capture disabled use the /o switch on the command-line.

As events are printed to the output, they are tagged with a sequence number. If Filemon’s internal buffers are overflowed during extremely heavy activity, this will be reflected with gaps in the sequence number.

Each time you exit FileMon it remembers the filters you've configured, position of the window and the widths of the output columns.

Filtering Use the Filter dialog, which is accessed with a toolbar button or the Edit|Filter/Highlight menu selection, to select what data will be shown in the list view. The '*' wildcard matches arbitrary strings, and the filters are case-insensitive. Only matches shown in the include filter, but that are not excluded with the exclude filter, are displayed. Use ';' to separate multiple strings in a filter (e.g. "filemon;temp"). Windows NT/2000 note: because of the asynchronous nature of file I/O, its not possible to filter on the result field.

Wildcards allow for complex pattern matching, making it possible to match specific file accesses by specific applications, for example. The include filter “Winword*Windows” would have FileMon only show accesses by Microsoft Word to files and directories that include the word “Windows”.

Use the highlight filter specify output that you want to have highlighted in the listview output. Select highlighting colors with Edit|Highlight Colors.

Additional filter options select or deselect read, write or open operations. In many troubleshooting scenarios only open operations are of interest, for example.