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UNITS(1)                  BSD General Commands Manual                 UNITS(1)

NAME
     units -- conversion program

SYNOPSIS
     units [-f filename] [-qv] [from-unit to-unit]

OPTIONS
     The following options are available:

     -f filename
             Specify the name of the units data file to load.

     -q      Suppress prompting of the user for units and the display of statistics about the number of
             units loaded.

     -v      Print the version number.

     from-unit to-unit
             Allow a single unit conversion to be done directly from the command line.  The program will not
             print prompts.  It will print out the result of the single specified conversion.

DESCRIPTION
     The units program converts quantities expressed in various scales to their equivalents in other scales.
     The units program can only handle multiplicative scale changes.  It cannot convert Celsius to Fahren-heit, Fahrenheit,
     heit, for example.  It 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

         You have: meters/s
         You want: furlongs/fortnight
                 * 6012.8848
                 / 0.00016630952

         You have: 1|2 inch
         You want: cm
                 * 1.27
                 / 0.78740157

     Powers of units can be specified using the '^' character as shown in the example, or by simple concate-nation: concatenation:
     nation: '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'.  Division of numbers
     must be indicated using the vertical bar ('|').  To convert half a meter, you would write '1|2 meter'.
     If you write '1/2 meter' then the units program would interpret that as equivalent to '0.5/meter'.  If
     you enter 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:

           pi         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 per unit height of water
           mercury    pressure per unit height of mercury
           au         astronomical unit

     The unit 'pound' is a unit of mass.  Compound names are run together so 'pound force' is a unit of
     force.  The unit 'ounce' is also a unit of mass.  The fluid ounce is 'floz'.  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 units will try to remove a trailing 's' or a trailing 'es' and check again
     for a match.

     To find out what units are available read the standard units file.  If you want to add your own units
     you can supply your own file.  A unit is specified on a single line by giving its name and an equiva-lence. equivalence.
     lence.  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.  The units program will not detect infinite loops that
     could be caused by careless unit definitions.  Comments in the unit definition file begin with a '/'
     character at the beginning of a line.

     Prefixes are defined in the same was as standard units, but with a trailing dash at the end of the pre-fix prefix
     fix name.  If a unit is not found even after removing trailing 's' or 'es', then it will be checked
     against the list of prefixes.  Prefixes will be removed until a legal base unit is identified.

     Here is an example of a short units file that defines some basic units.

           m         !a!
           sec       !b!
           micro-    1e-6
           minute    60 sec
           hour      60 min
           inch      0.0254 m
           ft        12 inches
           mile      5280 ft

FILES
     /usr/share/misc/units.lib  the standard units library

AUTHORS
     Adrian Mariano <adrian@cam.cornell.edu>

BUGS
     The effect of including a '/' in a prefix is surprising.

     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 dis-tinction distinction
     tinction 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 does not take so long to load the units
     list and check for duplication.

BSD                              July 14, 1993                             BSD