ntptime(8) on Linux
The text 891bfb406821, as Debian 9 (Stretch), Debian 8 (Jessie), Debian 7 (Wheezy), Debian 6.0 (Squeeze) shipped it.
read kernel time variables
Flags it lists
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-c -
-e -
-f -
-h -
-m -
-o -
-r -
-s -
-t