xmessage(1x) on Linux
The text d2a5bce87bc7, as Debian 2.2 (Potato), Debian 2.1 (Slink), Debian 2.0 (Hamm), Debian 1.3 (Bo) shipped it.
display a message or query in a window (X-based /bin/echo)
Flags it lists
-
-buttons -
-center -
-default -
-file -
-nearmouse -
-print -
-timeout