7 .Nd conversion calculator
17 program converts quantities expressed in various scales to
18 their equivalents in other scales.
20 handle multiplicative or affine scale changes.
23 can work interactively by prompting
26 or non-interactively, providing a conversion for given arguments
31 The following options are available:
32 .Bl -tag -width "from to"
33 .It Fl e , Fl -exponential
37 (see the description of the
40 .It Fl f Ar unitsfile , Fl -file Ar unitsfile
41 Specify the name of the units data file to load.
42 This option may be specified multiple times.
43 .It Fl H Ar historyfile , Fl -history Ar historyfile
44 Ignored, for compatibility with GNU units.
46 Show an overview of options.
47 .It Fl o Ar format , Fl -output-format Ar format
48 Select the output format string by which numbers are printed.
52 Suppress prompting of the user for units and the display of statistics
53 about the number of units loaded.
55 Only print the result.
56 This is used when calling
58 from other programs for easy to parse results.
59 .It Fl U , Fl -unitsfile
60 Print the location of the default unit file if it exists.
62 .Dq Units data file not found .
63 .It Fl V , Fl -version
64 Print the version number
65 .Pq which is fixed at Dq Fx units ,
66 the path to the units data file and exit.
67 .It Fl v , Fl -verbose
68 Print the units in the conversion output.
69 Be more verbose in general.
71 Allow a single unit conversion to be done directly from the command
73 The program will not print prompts.
74 It will print out the result of the single specified conversion.
83 or a quantity with a unit
86 .Ss Mathematical operators
89 Powers of units can be specified using the
91 character as shown in the example, or by simple concatenation:
99 for details on the limitations of exponent values.
101 Multiplication of units can be specified by using spaces
108 Division of units is indicated by the slash
112 must be indicated using the vertical bar
116 Note that multiplication has a higher precedence than division,
124 The conversion information is read from a units data file.
126 file includes definitions for most familiar units, abbreviations and
128 Some constants of nature included are:
130 .Bl -column -offset indent -compact "mercury"
131 .It "pi ratio of circumference to diameter"
132 .It "c speed of light"
133 .It "e charge on an electron"
134 .It "g acceleration of gravity"
135 .It "force same as g"
136 .It "mole Avogadro's number"
137 .It "water pressure per unit height of water"
138 .It "mercury pressure per unit height of mercury"
139 .It "au astronomical unit"
145 Compound names are run together
151 is also a unit of mass.
154 British units that differ from
155 their US counterparts are prefixed with
157 and currency is prefixed with its country name:
158 .Dq Ic belgiumfranc ,
159 .Dq Ic britainpound .
161 for a unit, if the specified string does not appear exactly as a unit
164 will try to remove a trailing
168 and check again for a match.
169 .Ss Units file format
170 To find out what units are available read the standard units file.
171 If you want to add your own units you can supply your own file.
172 A unit is specified on a single line by
173 giving its name and an equivalence.
175 new units in terms of old ones so that a reduction leads to the
176 primitive units which are marked with
181 program will not detect infinite loops that could be caused
182 by careless unit definitions.
183 Comments in the unit definition file
188 character at the beginning of a line.
190 Prefixes are defined in the same way as standard units, but with
193 at the end of the prefix name.
194 If a unit is not found
195 even after removing trailing
199 then it will be checked against the list of prefixes.
200 Prefixes will be removed until a legal
201 base unit is identified.
205 The colon-separated list of root directories at which
208 .Pa /usr/share/misc/definitions.units .
213 .Dq Li /tmp:/:/usr/local ,
216 flags are provided, and
217 .Pa /usr/share/misc/definitions.units
220 tries to open the following files as the default units file:
221 .Pa /tmp/usr/share/misc/definitions.units ,
222 .Pa /usr/share/misc/definitions.units ,
224 .Pa /usr/local/usr/share/misc/definitions.units .
227 .Bl -tag -width /usr/share/misc/definitions.units -compact
228 .It Pa /usr/share/misc/definitions.units
229 The standard units file.
235 .It Sy Example 1 : No Interactive usage
237 Here is an example of an interactive session where the user is prompted for
239 .Bd -literal -offset 2n
240 .Li You have : Ic meters
241 .Li You want : Ic feet
245 .Li You have : Ic cm^3
246 .Li You want : Ic gallons
250 .Li You have : Ic meters/s
251 .Li You want : Ic furlongs/fortnight
255 .Li You have : Ic 1|2 inch
260 .Li You have : Ic 85 degF
261 .Li You want : Ic degC
264 .It Sy Example 2 : No Difference between Do Ic \&| Dc No and Do Ic / Dc No division
266 The following command shows how to convert half a meter to centimeters.
267 .Bd -literal -offset 2n
268 .Li $ Ic units '1|2 meter' cm
274 prints the expected result because the division operator for numbers
278 Using the division operator for units
280 would result in an error:
281 .Bd -literal -offset 2n
282 .Li $ Ic units '1/2 meter' cm
294 which is not conformable to
296 .It Sy Example 3 : No Simple units file
297 Here is an example of a short units file that defines some basic
300 .Bl -column -offset 2n -compact "minute"
310 .It Sy Example 4 : No Viewing units and conversions of the default units file
311 The following shell one-liner allows the user to view the contents of the
313 .Bd -literal -offset 2n
314 .Li $ Ic less \&"$(units -U)"
319 .It can't find units file '%s'
320 The default units file is not in its default location
322 and it is not present in any file tree starting with their roots at directories from
324 .Pq see Sx ENVIRONMENT .
325 .It cap_rights_limit\&() failed
328 .It conformability error
329 It is not possible to reduce the given units to one common unit:
330 they are not conformable.
331 Instead of a conversion,
333 will display the reduced form for each provided unit:
334 .Bd -literal -offset 2n
335 .Li You have : Ic ergs/hour
336 .Li You want : Ic fathoms kg^2 / day
338 2.7777778e-11 kg m^2 / sec^3
339 2.1166667e-05 kg^2 m / sec
341 .It Could not initialize history
347 .It memory for prefixes exceeded in line %d
348 Over 100 prefixes were defined.
349 .It memory for units exceeded in line %d
350 Over 1000 prefixes were defined.
351 .It memory overflow in unit reduction
352 The requested conversion involves too many units
354 .It redefinition of prefix '%s' on line %d ignored
356 .It redefinition of unit '%s' on line %d ignored
358 .It unexpected end of prefix on line %d
360 .It unexpected end of unit on line %d
362 .It Units data file not found
363 The default units file is missing.
364 .It unable to enter capability mode
367 .It unable to open units file '%s'
368 One of the user-specified units files cannot be opened.
369 .It unit reduces to zero
371 .It unknown unit '%s'
372 The provided unit cannot be found in the units file.
373 .It WARNING: conversion of non-proportional quantities.
379 because the units are not proportional.
380 The warning is printed when a quantity is a part of the
383 It can be illustrated on an example of conversion from Fahrenheit to Celsius:
384 .Bd -literal -offset 2n
385 .Li $ Ic units \&"degF" \&"degC"
386 (-> x*0.55555556g -17.777778g)
388 .Li $ Ic units \&"degF" \&"1 degC"
389 WARNING: conversion of non-proportional quantities.
390 (-> x*0.55555556g -17.777778g)
392 .Li $ Ic units \&"1 degF" \&"1 degC"
393 WARNING: conversion of non-proportional quantities.
407 The manual page was significantly rewritten in
410 .An Mateusz Piotrowski Aq Mt 0mp@FreeBSD.org .
412 .An Adrian Mariano Aq Mt adrian@cam.cornell.edu
414 The effect of including a
416 in a prefix is surprising.
418 Exponents entered by the user can be only one digit.
419 You can work around this by multiplying several terms.
423 to indicate division of numbers and
425 to indicate division of symbols.
426 This distinction should not
429 The program contains various arbitrary limits on the length
430 of the units converted and on the length of the data file.
432 The program should use a hash table to store units so that
433 it does not take so long to load the units list and check
436 It is not possible to convert a negative value.
441 does not handle reductions of long lists of units very well:
442 .Bd -literal -offset 2n
443 .Li $ Ic units \&"$(yes m | head -n 154)" \&"$(yes cm | head -n 154)"
446 .Li $ Ic units \&"$(yes m | head -n 333)" \&"$(yes cm | head -n 333)"
449 .Li $ Ic units \&"$(yes m | head -n 500)" \&"$(yes cm | head -n 500)"
450 units: memory overflow in unit reduction
454 .Li $ Ic units \&"$(yes m | head -n 501)" \&"$(yes cm | head -n 501)"
455 units: memory overflow in unit reduction
456 units: memory overflow in unit reduction
457 units: memory overflow in unit reduction