grdrotater(1gmt) on Linux
The text a5fc5feb1166, as Debian 7 (Wheezy) shipped it.
Rotate a grid using a finite rotation
Flags it lists
-
-: -
-F -
-G -
-H -
-N -
-Q -
-R -
-S -
-T -
-V -
-bi -
-bo -
-m