"Instruments" is an application provided by Apple that provides a graphical user interface for the DTrace command-line tool. DTrace is a troubleshooting tool available on several Unix-like operating systems, including Mac OS X. It can log and provide statistics for many application and kernel-level operations.
NOTE: Instruments and the required Xcode installation can be unwieldy. Also, the newer SEP client for Macintosh (as of SEP 12.1 RU4) and SymDaemon process are not visible to Instruments tracing. Use the fs_usage command line to trace SymDaemon file activity instead.
How to Install
To install Instruments, you must install Xcode, the Macintosh development tools. Xcode is free and can be obtained via the following means:
Please note: Xcode is a very large download and depending on network speeds may take some time to fully download. Please use the most up to date version of Xcode for your environment to ensure compatibility.
How to use Instruments
This procedure can easily be adjusted to trace only specific processes and executables, but for our purposes here you will be shown how to monitor CPU and file activity for all processes.
Don't be intimidated by the choices that appear. For our purposes, choose "System Call", "open*", "arg0", and "path". Click the plus (+) button to the right of "arg0/path", to add another data item to record: executable name. See image below for these highlighted items.
If desired, you can also click the plus (+) button to the right of "System Call/open*" and add further logging conditions.
For example, you could add Executable=="navx" to log only those file activities related to the navx process. Normally, we will not add any conditions, and log all activity.
Click "Save" in the custom instrument dialog when you are done.
You can then select your custom "DTrace Instrument" which will display and highlight file activity that occured during the time selected, as you drag the position indicator (the upside-down triangle in the time scale at top):
You can also export the file activity to a CSV text file for grepping and other filtering you might want to do: while your "DTrace Instrument" is selected, choose "Export track..." from the Instrument menu.
Several Xcode versions are available at http://connect.apple.com. An AppleID is required (is available upon free registration). Look for Xcode under "Developer Tools". Xcode 3.2.5 is a 3.5GB download.