rdate(8) on Linux
The text 86a7668cb78a, as Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie), Debian 7 (Wheezy), Debian 6.0 (Squeeze), Debian 5.0 (Lenny) shipped it.
set the system's date from a remote host
Flags it lists
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-4 -
-6 -
-a -
-c -
-n -
-o -
-p -
-s -
-u -
-v