Discovering a new UNIX tool

December 22, 2023 — Nico Cartron

When reading that article - which by the way is worth having a look at! - I discovered a new UNIX tool which I wasn't aware of: units

units is a conversion calculator - from its man page (UNITS(1)):

The units program converts quantities expressed in various scales to
their equivalents in other scales.

Fun! I wasn't aware of this nice tool.

Trying units

It is available on a default FreeBSD install, let's give it a try!

% units
586 units, 56 prefixes
You have:

Right, so you need to answer to "You have" with the initial quantity and unit, and then specify to which unit you want to convert to.

Let's try converting 3 kilometers to miles:

You have: 3 kms
You want: miles
    * 1.8641136
    / 0.536448

=> 3 kilometers makes ~1.86 miles.
The last line gives you the calculation that units used.

Now let's convert an hour to seconds:

You have: 1 hour
You want: seconds
    * 3600
    / 0.00027777778

And finally 2 days to minutes:

You have: 2 days
You want: minutes
    * 2880
    / 0.00034722222

Sure you can try converting to something completely crazy, but units will complain - e.g. convertings 3 milliseconds to miles!

You have: 3 milliseconds
You want: miles
conformability error
    0.003 sec
    1609.344 m