xwd(1x) on Linux
The text 914fb368a54e, as Debian 1.1 (Buzz) shipped it.
dump an image of an X window
Flags it lists
-
-add -
-display -
-frame -
-help -
-icmap -
-id -
-name -
-nobdrs -
-out -
-root -
-screen -
-xy