gmttrack(1gmt) on Linux
The text 18d50c29a6cf, as Debian 7 (Wheezy) shipped it.
A shiptrack plotting program
Flags it lists
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-A -
-B -
-Da -
-Db -
-J -
-K -
-M -
-O -
-P -
-R -
-Sa -
-Sb -
-U -
-V -
-W -
-X -
-Y -
-c