Converts units in one measure to equivalent units in another measure.

**units **[ **-**** **] [ *File *]

The **units** command converts quantities expressed in one measurement to their equivalents in another. The **units** command is an interactive command. It prompts you for the unit you want to convert *from* and the unit you want to convert *to*. This command only does multiplicative scale changes. That is, it can convert from one value to another only when the conversion involves a multiplication. For example, it cannot convert between degrees Fahrenheit and degrees Celsius because the value of 32 must be added or subtracted in the conversion.

You can specify a quantity as a multiplicative combination of units, optionally preceded by a numeric multiplier.

Indicate powers by entering suffixed positive integers, and indicate division with a / (slash).

The **units** command recognizes `lb`
as a unit of mass, but considers `pound`
to be the British pound sterling. Compound names are run together (such as `lightyear`
). Prefix British units differing from their American counterparts with `br`
(`brgallon`
, for instance).

The **/usr/share/lib/unittab** file contains a complete list of the units that the **units** command uses. You can also define new units in this file. The *File* parameter may be used to override the values of the standard conversion factors listed in the **/usr/share/lib/unittab** file. The specified file must follow the same format as the **unittab** file.

Most familiar units, abbreviations, and metric prefixes are recognized by the **units** command, as well as the following:

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 head per unit height of water |

au |
Astronomical unit |

- |
Lists the conversion factors contained in the /usr/share/lib/unittab file before you are prompted to enter your conversion. |

- To display conversion factors for inches to centimeters, enter:
units you have: in you want: cm

The**units**command returns the following values:* 2.540000e+00 / 3.937008e-01

The output tells you to multiply the number of inches by`2.540000e+00`to get centimeters, and to multiply the number of centimeters by`3.937008e-01`to get inches.These numbers are in standard exponential notation, so

`3.937008e-01`means`3.937008 x 10``-1`, which is the same as`0.3937008`.**Note:**The second number is always the reciprocal of the first; for example,`2.54`equals`1/0.3937008`. - To convert a measurement to different units, enter:
units you have: 5 years you want: microsec

The**units**command returns the following values:* 1.577846e+14 / 6.337753e-15

The output shows that`5 years`equals`1.577846 x 10``14`microseconds, and that one microsecond equals`6.337753 x 10``-15`years. - To give fractions in measurements, enter:
units you have: 1|3 mi you want: km

The**units**command returns the following values:* 5.364480e-01 / 1.864114e+00

The | (vertical bar) indicates division, so`1|3`means one-third. This shows that one-third mile is the same as`0.536448`kilometers. - To include exponents in measurements, enter:
units you have: 1.2-5 gal you want: floz

The**units**command returns the following values:* 1.536000e-03 / 6.510417e+02

The expression`1.2-5 gal`is the equivalent of`1.2 x 10``-5`. Do*not*type an`e`before the exponent (that is,`1.2e-5 gal`is not valid). This example shows that`1.2 x 10``-5``(0.000012)`gallons equal`1.536 x 10``-3``(0.001536)`fluid ounces. - To specify complex units, enter:
units you have: gram centimeter/second2 you want: kg-m/sec2

The**units**command returns the following values:* 1.000000e-05 / 1.000000e+05

The units`gram centimeter/second2`mean "grams x centimeters/second2." Similarly,`kg-m/sec2`means "kilograms x meters/sec2," which is often read as "kilogram-meters per seconds squared." - If the units you specify after
`you have:`and`you want:`are incompatible:you have: ft you want: lb

The**units**command returns the following message and values:conformability 3.048000e-01 m 4.535924e-01 kg

The`conformability`message means the units you specified cannot be converted. Feet measure length, and pounds measure mass, so converting from one to the other does not make sense. Therefore, the**units**command displays the equivalent of each value in standard units.In other words, this example shows that one foot equals

`0.3048`meters and that one pound equals`0.4535924`kilograms. The**units**command shows the equivalents in meters and kilograms because the command considers these units to be the standard measures of length and mass.

/usr/bin/units |
Contains the units command. |

/usr/share/lib/unittab |
Lists units that the units command creates as well as units defined by the user. |