psclip(1gmt) on Linux
The text b8b905475f54, as Debian 7 (Wheezy) shipped it.
To set up polygonal clip paths
Flags it lists
-
-: -
-B -
-C -
-E -
-H -
-J -
-K -
-N -
-O -
-P -
-R -
-T -
-U -
-V -
-X -
-Y -
-Z -
-bi -
-c -
-f -
-m