
Units converts quantities expressed in various standard scales
to their equivalents in other scales. It works interactively in
this fashion:
 
you have: inch
you want: cm

A quantity is specified as a multiplicative combination of units
and floating point numbers. Operators have the following precedence:
 
+ – add and subtract
* / x ÷ multiply and divide
catenation multiply
² ³ ^ exponentiation
 divide
( ... ) grouping

Most familiar units, abbreviations, and metric prefixes are recognized,
together with a generous leavening of exotica and a few constants
of nature including:
 
pi,π ratio of circumference to diameter
c speed of light
e charge on an electron
g acceleration of gravity
force same as g
mole Avogadro's number
water pressure head per unit height of water
au astronomical unit

The pound is a unit of mass. Compound names are run together,
e.g. lightyear. British units that differ from their US counterparts
are prefixed thus: brgallon. Currency is denoted belgiumfranc,
britainpound, etc.
The complete list of units can be found in /lib/units. A file
argument to units specifies a file to be used instead of /lib/units.
The –v flag causes units to print its entire database.
