diff options
Diffstat (limited to 'usr.bin/units/units.1')
| -rw-r--r-- | usr.bin/units/units.1 | 59 |
1 files changed, 40 insertions, 19 deletions
diff --git a/usr.bin/units/units.1 b/usr.bin/units/units.1 index c811dac9ff41..13ed413b155a 100644 --- a/usr.bin/units/units.1 +++ b/usr.bin/units/units.1 @@ -22,18 +22,23 @@ about the number of units loaded. Print the version number. .It Ar 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 +line. +The program will not print prompts. +It will print out the result of the single specified conversion. .El .Sh DESCRIPTION The .Nm program converts quantities expressed in various scales to -their equivalents in other scales. The +their equivalents in other scales. +The .Nm program can only -handle multiplicative scale changes. It cannot convert Celsius -to Fahrenheit, for example. It works interactively by prompting +handle multiplicative scale changes. +It cannot convert Celsius +to Fahrenheit, for example. +It works interactively by prompting the user for input: .Bd -literal You have: meters @@ -60,11 +65,15 @@ the user for input: 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 ('/'). +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 +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 @@ -77,9 +86,11 @@ it will display the reduced form for each unit: 2.1166667e-05 kg^2 m / sec .Ed .Pp -The conversion information is read from a units data file. The default +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: +metric prefixes. +Some constants of nature included are: .Pp .Bl -column -offset indent -compact "mercury" .It "pi ratio of circumference to diameter @@ -93,11 +104,16 @@ metric prefixes. Some constants of nature included are: .It "au astronomical unit .El .Pp -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 +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 +with its country name: 'belgiumfranc', 'britainpound'. +When searching for a unit, if the specified string does not appear exactly as a unit name, then .Nm @@ -107,19 +123,23 @@ 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 equivalence. Be careful to define +giving its name and an equivalence. +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 .Nm program will not detect infinite loops that could be caused -by careless unit definitions. Comments in the unit definition file +by careless unit definitions. +Comments in the unit definition file begin with a '/' character at the beginning of a line. .Pp Prefixes are defined in the same was as standard units, but with -a trailing dash at the end of the prefix name. If a unit is not found +a trailing dash at the end of the prefix 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 +against the list of prefixes. +Prefixes will be removed until a legal base unit is identified. .Pp Here is an example of a short units file that defines some basic @@ -142,7 +162,8 @@ Exponents entered by the user can be only one digit. You can work around this by multiplying several terms. .Pp The user must use | to indicate division of numbers and / to -indicate division of symbols. This distinction should not +indicate division of symbols. +This distinction should not be necessary. .Pp The program contains various arbitrary limits on the length |