-.B \-C
-Display completion/progress bars for those filesystems checkers (currently
-only for ext2) which support them. Fsck will manage the filesystem checkers
-so that only one of them will display a progress bar at a time.
+.B \-C\fR [ \fI "fd" \fR ]
+Display completion/progress bars for those filesystem checkers (currently
+only for ext2 and ext3) which support them. Fsck will manage the
+filesystem checkers so that only one of them will display
+a progress bar at a time. GUI front-ends may specify a file descriptor
+.IR fd ,
+in which case the progress bar information will be sent to that file descriptor.
+.TP
+.B \-M
+Do not check mounted filesystems and return an exit code of 0
+for mounted filesystems.