Note on new MacOS builds you will likely have to boot into recovery and run:
csrutil enable --without dtrace
Otherwise you'll get a permissions error due to recent MacOS code signing protection... unless you copy the program you want to analyze to /tmp as a work around.
Also, on OSX you have access to (mostly) the full power of dtrace, so you can do diagnostics on closed-source, debug-stripped running programs that make strace look small by comparison.
