join(1) on Linux
The text ac257a19d2f5, as Debian 5.0 (Lenny) shipped it.
join lines of two files on a common field
Flags it lists
-
--help -
--ignore-case -
--version -
-1 -
-2 -
-a -
-e -
-i -
-j -
-o -
-t -
-v