A reminder that GNU Units still exists,
e.g. $ units
Currency exchange rates from FloatRates (USD base) on 2021-01-17
3677 units, 109 prefixes, 114 nonlinear units
You have: 4 amu * (1000 nm/s)^2
You want: joules
* 6.6421563e-39
/ 1.5055352e+38
You have: ^D
It’s slightly less DWIMish (you have to say “atomicmassunits”, “atomicmassunit”, “amu”, or “u”, not “atomic mass units”) and somewhat awkward as a separate tool, but then resorting to your web browser for unit conversions is awkward in a different way. Non-interactive invocations, like
units VALUE-OR-UNIT UNIT, work as well.
[1]: https://www.gnu.org/software/units/
