units -- Command

Convert measurements
units [ -u ]

units is an  interactive program that tells you how  to convert one unit of
measurement into another.  It prompts  you for two quantities with the same
dimension (e.g.,  two measurements  of weight, or  two of size).   It first
prints the  prompt ``You have:''  to ask for  the unit you  wish to convert
from, and  then prints the  prompt ``You want:''  for the unit  you wish to
convert to.

Example

The following example returns the formula for convert fortnights into days:

    You have: fortnight
    You want: days
    * 14
    / 0.071428

The  following  fundamental  units  are  recognized: meter,  gram,  second,
coulomb,  radian,  bit,  unitedstatesdollar,  sheet,  candle,  kelvin,  and
copperpiece (shillings and pence).

A  quantity consists  of an  optional number (default,  1) and  a dimension
(default, none).   Numbers are floating  point with optional  sign, decimal
part and  exponent.  Dimensions may be specified  by fundamental or derived
units,  with optional  orders.  A  quantity is evaluated  left to  right: a
factor preceded by  a `/' is a divisor, otherwise  it is a multiplier.  For
example, the  earth's gravitational acceleration  may be entered  as any of
the following:

    9.8e+0 m+1 sec-2
    32 ft/sec/sec
    32 ft/sec+2

British equivalents  of US units are prefixed with  br, e.g., brpint. Other
units include  c (speed of  light), G (gravitational  constant), R (gas-law
constant), phi (golden ratio) % (1/100), k (1,024), and buck (United States
dollar).

/usr/lib/units  is the  ASCII file  that  contains conversion  tables.  The
binary file /usr/lib/binunits may be recreated by using the -u option.

Files

/usr/lib/units -- Known units
/usr/lib/binunits -- Binary encoding of units file

See Also

bc,
commands,
conv

Diagnostics

If the ASCII file /usr/lib/units  has changed more recently than the binary
file /usr/lib/binunits,  units prints a message  and regenerates the binary
file before it continues; this can take up to a few minutes, depending upon
the speed of your system.

The  error message  ``conformability'' means  that  the quantities  are not
dimensionally compatible,  e.g., m/sec and psi.  units prints each quantity
and its dimensions in fundamental units.

Notes

There are the inevitable name collisions: g for gram versus gee for Earth's
gravitational acceleration, exp for the base of natural logarithms versus e
for the  charge of an electron, ms for  (plural) meters versus millisecond,
and, of  course, batman for the  Persian measure of weight  rather than the
Turkish.

© 2012 by Stephen A. Ness