| UNITS(1) | General Commands Manual | UNITS(1) | 
units —
| units | [ -Llqv] [-ffilename] [[count]
      from-unit to-unit] | 
units converts quantities expression in various scales
  to their equivalents in other scales. units can only
  handle multiplicative scale changes. It cannot convert Centigrade to
  Fahrenheit, for example.
The following options and arguments are supported:
-f
    filename-l
    or -L/’.
    With the -l option, unit definitions
        will be listed in a format almost identical to the units data file that
        was loaded, except that comments will be removed, spacing may be
        changed, and lines may be re-ordered.
With the -L option, all unit
        definitions will be reduced to a form that depends on only a few
        primitive units (such as m, kg,
        sec).
-q-vunits will print out only
      the result of this single conversion. Specifying
      count and from-unit as two
      separate arguments is equivalent to embedding both parts inside a single
      from-unit argument, with the parts separated by a
      space.units works interactively by prompting the
    user for input:
    You have: meters
    You want: feet
            * 3.2808399
            / 0.3048
    You have: cm^3
    You want: gallons
            * 0.00026417205
            / 3785.4118
Powers of units can be specified using the “^”
    character as shown in the example, or by simple concatenation:
    “cm3” is equivalent to “cm^3”. Multiplication of
    units can be specified by using spaces, a dash or an asterisk. Division of
    units is indicated by the slash (‘/’). Note that
    multiplication has a higher precedence than division, so
    “m/s/s” is the same as “m/s^2” or “m/s
    s”. If the user enters incompatible unit types, the
    units program will print a message indicating that
    the units are not conformable and it will display the reduced form for each
    unit:
    You have: ergs/hour
    You want: fathoms kg^2 / day
    conformability error
            2.7777778e-11 kg m^2 / sec^3
            2.1166667e-05 kg^2 m / sec
The conversion information is read from a units data file. The default file includes definitions for most familiar units, abbreviations and metric prefixes. Some constants of nature included are:
“pound” is a unit of mass. Compound names are run
    together so “poundforce” is a unit of force. British units
    that differ from their US counterparts are prefixed with “br”,
    and currency is prefixed with its country name:
    “belgiumfranc”, “britainpound”. When searching
    for a unit, if the specified string does not appear exactly as a unit name,
    then the units program will try to remove a trailing
    “s” or a trailing “es” and check again for a
    match.
All of these definitions can be read in the standard units file,
    or you can supply your own file. A unit is specified on a single line by
    giving its name and an equivalence. One should be careful to define new
    units in terms of old ones so that a reduction leads to the primitive units
    which are marked with ‘!’ characters.
    units will not detect infinite loops that could be
    caused by careless unit definitions.
Prefixes are defined in the same way as standard units, but with a trailing dash at the end of the prefix name.
units can be used as a calculator for many
  unit-related computations, caution is required: many computations require
  additional constant factors deriving from the physics (or chemistry or
  whatever) of the situation. As these factors are dimensionless,
  units cannot itself either provide them or warn the
  user when they have been forgotten. For example, one joule is one kilogram
  meter squared per second squared, by definition; however, the kinetic energy
  of a one-kilogram object moving at one meter per second is half a joule, not
  one joule, because of a dimensionless factor that arises from integration.
Also, some pairs of units that have the same dimensionality are
    nonetheless used to measure different things and attempting to convert
    between them may require additional fudge factors or be entirely
    meaningless. For example, torque and energy have the same dimensionality,
    but attempting to convert torque in newton-meters to energy in joules is
    nonsensical. There is no practical way for units to
    warn about these issues either.
Exponents entered by the user can be only one digit. You can work around this by multiplying several terms.
The user must use ‘|’ to indicate division of numbers and ‘/’ to indicate division of symbols. This distinction should not be necessary.
The program contains various arbitrary limits on the length of the units converted and on the length of the data file.
The program should use a hash table to store units so that it doesn't take so long to load the units list and check for duplication.
| January 6, 2013 | NetBSD 10.0 |