git-fsck tests SHA-1 and general object sanity, and it does full tracking
of the resulting reachability and everything else. It prints out any
corruption it finds (missing or bad objects), and if you use the
-'--unreachable' flag it will also print out objects that exist but that
+`--unreachable` flag it will also print out objects that exist but that
aren't reachable from any of the specified head nodes (or the default
set, as mentioned above).