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Index: head/usr.bin/units/units.1
===================================================================
--- head/usr.bin/units/units.1
+++ head/usr.bin/units/units.1
@@ -1,115 +1,126 @@
.\" $FreeBSD$
-.Dd August 12, 2017
+.Dd February 3, 2020
.Dt UNITS 1
.Os
.Sh NAME
.Nm units
-.Nd conversion program
+.Nd conversion calculator
.Sh SYNOPSIS
.Nm
-.Op Fl f Ar filename
-.Op Fl H Ar filename
-.Op Fl qvUV
-.Op Ar from-unit to-unit
-.Sh OPTIONS
+.Op Fl ehqtUVv
+.Op Fl f Ar unitsfile
+.Op Fl o Ar format
+.Op Ar from to
+.Sh DESCRIPTION
+The
+.Nm
+program converts quantities expressed in various scales to
+their equivalents in other scales.
+It can only
+handle multiplicative or affine scale changes.
+.Pp
+.Nm
+can work interactively by prompting
+the user for input
+.Pq see Sx EXAMPLES
+or non-interactively, providing a conversion for given arguments
+.Ar from
+and
+.Ar to .
+.Pp
The following options are available:
-.Bl -tag -width indent
-.It Fl h \&No , Fl -help
-Show an overview of options
-.It Fl f Ar filename \&No , Fl -file Ar filename
+.Bl -tag -width "from to"
+.It Fl e , Fl -exponential
+Same as
+.Fl o
+.Cm %6e
+(see the description of the
+.Fl o
+flag).
+.It Fl f Ar unitsfile , Fl -file Ar unitsfile
Specify the name of the units data file to load.
-.It Fl H Ar filename \&No , Fl -history Ar filename
+This option may be specified multiple times.
+.It Fl H Ar historyfile , Fl -history Ar historyfile
Ignored, for compatibility with GNU units.
-.It Fl e , Fl -exponential
-Behave as if -o '%6e' was typed.
-.It Fl q \&No , Fl -quiet
+.It Fl h , Fl -help
+Show an overview of options.
+.It Fl o Ar format , Fl -output-format Ar format
+Select the output format string by which numbers are printed.
+Defaults to
+.Dq Li %.8g .
+.It Fl q , Fl -quiet
Suppress prompting of the user for units and the display of statistics
about the number of units loaded.
-.It Fl U \&No , Fl -unitsfile
-If the default unit file exists prints its location.
-If not, print
-.Qo
-Units data file not found
-.Qc
-.It Fl t \&No , Fl -terse
-Only print the result. This is used when calling
+.It Fl t , Fl -terse
+Only print the result.
+This is used when calling
.Nm
from other programs for easy to parse results.
-.It Fl v \&No , Fl -verbose
+.It Fl U , Fl -unitsfile
+Print the location of the default unit file if it exists.
+Otherwise, print
+.Dq Units data file not found .
+.It Fl V , Fl -version
+Print the version number
+.Pq which is fixed at Dq Fx units ,
+the path to the units data file and exit.
+.It Fl v , Fl -verbose
Print the units in the conversion output.
Be more verbose in general.
-.It Fl o Ar format \&No , Fl -output-format Ar format
-Select the output format string by which numbers are printed.
-.It Fl V \&No , Fl -version
-Print the version number, usage, and then exit.
-.It Ar from-unit to-unit
+.It Ar from to
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.
+It will print out the result of the single specified conversion.
+Both arguments, i.e.,
+.Ar from
+and
+.Ar to ,
+can be just a unit
+.Pq e.g., Dq Cm cm ,
+a quantity
+.Pq e.g., Dq Cm 42 ,
+or a quantity with a unit
+.Pq e.g., Dq Cm 42 cm
.El
-.Sh DESCRIPTION
-The
-.Nm
-program converts quantities expressed in various scales to
-their equivalents in other scales.
-The
-.Nm
-program can only
-handle multiplicative or affine scale changes.
-It works interactively by prompting
-the user for input:
-.Bd -literal
- 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
-
- You have: 85 degF
- You want: degC
- 29.444444
-.Ed
-.Pp
-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 ('/').
-Note that multiplication has a higher precedence than division,
-so 'm/s/s' is the same as 'm/s^2' or 'm/s s'.
+.Ss Mathematical operators
+.Bl -dash -compact
+.It
+Powers of units can be specified using the
+.Dq Ic ^
+character as shown in the example, or by simple concatenation:
+.Dq Ic cm3
+is
+equivalent to
+.Dq Ic cm^3 .
+See the
+.Sx BUGS
+section
+for details on the limitations of exponent values.
+.It
+Multiplication of units can be specified by using spaces
+.Pq Dq " " ,
+a dash
+.Pq Dq -
+or an asterisk
+.Pq Dq * .
+.It
+Division of units is indicated by the slash
+.Pq Dq Ic / .
+.It
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:
-.Bd -literal
- 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
-.Ed
+must be indicated using the vertical bar
+.Pq Dq Ic \&| Ns .
+.El
.Pp
+Note that multiplication has a higher precedence than division,
+so
+.Dq Ic m/s/s
+is the same as
+.Dq Ic m/s^2
+or
+.Dq Ic m/s s .
+.Ss Units
The conversion information is read from a units data file.
The default
file includes definitions for most familiar units, abbreviations and
@@ -128,48 +139,165 @@
.It "au astronomical unit"
.El
.Pp
-The unit 'pound' is a unit of mass.
+The unit
+.Dq Ic 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'.
+so
+.Dq Ic pound force
+is a unit of force.
+The unit
+.Dq Ic ounce
+is also a unit of mass.
+The fluid ounce is
+.Dq Ic floz .
British units that differ from
-their US counterparts are prefixed with 'br', and currency is prefixed
-with its country name: 'belgiumfranc', 'britainpound'.
+their US counterparts are prefixed with
+.Dq br ,
+and currency is prefixed with its country name:
+.Dq Ic belgiumfranc ,
+.Dq Ic britainpound .
When searching
for a unit, if the specified string does not appear exactly as a unit
name, then
.Nm
-will try to remove a trailing 's' or a
-trailing 'es' and check again for a match.
-.Pp
+will try to remove a trailing
+.Dq s
+or a trailing
+.Dq es
+and check again for a match.
+.Ss Units file format
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
new units in terms of old ones so that a reduction leads to the
-primitive units which are marked with '!' characters.
+primitive units which are marked with
+.Dq \&!
+characters.
The
.Nm
program will not detect infinite loops that could be caused
by careless unit definitions.
Comments in the unit definition file
-begin with a '#' or '/' character at the beginning of a line.
+begin with a
+.Dq #
+or
+.Dq /
+character at the beginning of a line.
.Pp
Prefixes are defined in the same way as standard units, but with
-a trailing dash at the end of the prefix name.
+a trailing dash
+.Pq Dq -
+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.
+even after removing trailing
+.Dq s
+or
+.Dq es ,
+then it will be checked against the list of prefixes.
Prefixes will be removed until a legal
base unit is identified.
+.Sh ENVIRONMENT
+.Bl -tag -width PATH
+.It Ev PATH
+The colon-separated list of root directories at which
+.Nm
+tries to find
+.Pa /usr/share/misc/definitions.units .
.Pp
+For example if
+.Ev PATH
+is set to
+.Dq Li /tmp:/:/usr/local ,
+no
+.Fl f
+flags are provided, and
+.Pa /usr/share/misc/definitions.units
+is missing then
+.Nm
+tries to open the following files as the default units file:
+.Pa /tmp/usr/share/misc/definitions.units ,
+.Pa /usr/share/misc/definitions.units ,
+and
+.Pa /usr/local/usr/share/misc/definitions.units .
+.El
+.Sh FILES
+.Bl -tag -width /usr/share/misc/definitions.units -compact
+.It Pa /usr/share/misc/definitions.units
+The standard units file.
+.El
+.Sh EXIT STATUS
+.Ex -std
+.Sh EXAMPLES
+.Bl -tag -width 0n
+.It Sy Example 1 : No Interactive usage
+.Pp
+Here is an example of an interactive session where the user is prompted for
+units:
+.Bd -literal -offset 2n
+.Li You have : Ic meters
+.Li You want : Ic feet
+ * 3.2808399
+ / 0.3048
+
+.Li You have : Ic cm^3
+.Li You want : Ic gallons
+ * 0.00026417205
+ / 3785.4118
+
+.Li You have : Ic meters/s
+.Li You want : Ic furlongs/fortnight
+ * 6012.8848
+ / 0.00016630952
+
+.Li You have : Ic 1|2 inch
+.Li You want : Ic cm
+ * 1.27
+ / 0.78740157
+
+.Li You have : Ic 85 degF
+.Li You want : Ic degC
+ 29.444444
+.Ed
+.It Sy Example 2 : No Difference between Do Ic \&| Dc No and Do Ic / Dc No division
+.Pp
+The following command shows how to convert half a meter to centimeters.
+.Bd -literal -offset 2n
+.Li $ Ic units '1|2 meter' cm
+ * 50
+ / 0.02
+.Ed
+.Pp
+.Nm
+prints the expected result because the division operator for numbers
+.Pq Dq Li \&|
+was used.
+.Pp
+Using the division operator for units
+.Pq Dq Li /
+would result in an error:
+.Bd -literal -offset 2n
+.Li $ Ic units '1/2 meter' cm
+conformability error
+ 0.5 / m
+ 0.01 m
+.Ed
+.Pp
+It is because
+.Nm
+interprets
+.Dq Ic 1/2 meter
+as
+.Dq Ic 0.5/meter ,
+which is not conformable to
+.Dq Ic cm .
+.It Sy Example 3 : No Simple units file
Here is an example of a short units file that defines some basic
-units.
+units:
.Pp
-.Bl -column -offset indent -compact "minute"
+.Bl -column -offset 2n -compact "minute"
.It "m !a!"
.It "sec !b!"
.It "micro- 1e-6"
@@ -179,21 +307,122 @@
.It "ft 12 inches"
.It "mile 5280 ft"
.El
-.Sh FILES
-.Bl -tag -width /usr/share/misc/definitions.units -compact
-.It Pa /usr/share/misc/definitions.units
-the standard units library
+.It Sy Example 4 : No Viewing units and conversions of the default units file
+The following shell one-liner allows the user to view the contents of the
+default units file:
+.Bd -literal -offset 2n
+.Li $ Ic less \&"$(units -U)"
+.Ed
.El
+.Sh DIAGNOSTICS
+.Bl -diag
+.It can't find units file '%s'
+The default units file is not in its default location
+.Pq see Sx FILES
+and it is not present in any file tree starting with their roots at directories from
+.Ev PATH
+.Pq see Sx ENVIRONMENT .
+.It cap_rights_limit\&() failed
+See
+.Xr capsicum 4 .
+.It conformability error
+It is not possible to reduce the given units to one common unit:
+they are not conformable.
+Instead of a conversion,
+.Nm
+will display the reduced form for each provided unit:
+.Bd -literal -offset 2n
+.Li You have : Ic ergs/hour
+.Li You want : Ic fathoms kg^2 / day
+conformability error
+ 2.7777778e-11 kg m^2 / sec^3
+ 2.1166667e-05 kg^2 m / sec
+.Ed
+.It Could not initialize history
+See
+.Xr editline 3 .
+.It dupstr
+.Xr strdup 3
+failed.
+.It memory for prefixes exceeded in line %d
+Over 100 prefixes were defined.
+.It memory for units exceeded in line %d
+Over 1000 prefixes were defined.
+.It memory overflow in unit reduction
+The requested conversion involves too many units
+.Pq see Sx BUGS .
+.It redefinition of prefix '%s' on line %d ignored
+.No ""
+.It redefinition of unit '%s' on line %d ignored
+.No ""
+.It unexpected end of prefix on line %d
+.No ""
+.It unexpected end of unit on line %d
+.No ""
+.It Units data file not found
+The default units file is missing.
+.It unable to enter capability mode
+See
+.Xr capsicum 4 .
+.It unable to open units file '%s'
+One of the user-specified units files cannot be opened.
+.It unit reduces to zero
+.No ""
+.It unknown unit '%s'
+The provided unit cannot be found in the units file.
+.It WARNING: conversion of non-proportional quantities.
+.Nm
+may fail to convert
+.Ar from
+to
+.Ar to
+because the units are not proportional.
+The warning is printed when a quantity is a part of the
+.Ar to
+argument.
+It can be illustrated on an example of conversion from Fahrenheit to Celsius:
+.Bd -literal -offset 2n
+.Li $ Ic units \&"degF" \&"degC"
+ (-> x*0.55555556g -17.777778g)
+ (<- y*1.8g 32g)
+.Li $ Ic units \&"degF" \&"1 degC"
+WARNING: conversion of non-proportional quantities.
+ (-> x*0.55555556g -17.777778g)
+ (<- y*1.8g 32g)
+.Li $ Ic units \&"1 degF" \&"1 degC"
+WARNING: conversion of non-proportional quantities.
+ -17.222222
+.Ed
+.El
+.Sh SEE ALSO
+.Xr bc 1
+.Sh HISTORY
+The
+.Nm
+first appeared in
+.Nx
+and was ported to
+.Fx 2.2.0 .
+.Pp
+The manual page was significantly rewritten in
+.Fx 13.0
+by
+.An Mateusz Piotrowski Aq Mt 0mp@FreeBSD.org .
.Sh AUTHORS
.An Adrian Mariano Aq Mt adrian@cam.cornell.edu
.Sh BUGS
-The effect of including a '/' in a prefix is surprising.
+The effect of including a
+.Dq /
+in a prefix is surprising.
.Pp
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.
+The user must use
+.Dq Ic \&|
+to indicate division of numbers and
+.Dq Ic /
+to indicate division of symbols.
This distinction should not
be necessary.
.Pp
@@ -203,3 +432,30 @@
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.
+.Pp
+It is not possible to convert a negative value.
+.Pp
+The
+.Nm
+program
+does not handle reductions of long lists of units very well:
+.Bd -literal -offset 2n
+.Li $ Ic units \&"$(yes m | head -n 154)" \&"$(yes cm | head -n 154)"
+ * 1e+308
+ / 1e-308
+.Li $ Ic units \&"$(yes m | head -n 333)" \&"$(yes cm | head -n 333)"
+ * inf
+ / 0
+.Li $ Ic units \&"$(yes m | head -n 500)" \&"$(yes cm | head -n 500)"
+units: memory overflow in unit reduction
+conformability error
+ 1 m^500
+ 1 centi cm^499
+.Li $ Ic units \&"$(yes m | head -n 501)" \&"$(yes cm | head -n 501)"
+units: memory overflow in unit reduction
+units: memory overflow in unit reduction
+units: memory overflow in unit reduction
+conformability error
+ 1 m^500
+ 1 centi cm^499
+.Ed
Index: head/usr.bin/units/units.c
===================================================================
--- head/usr.bin/units/units.c
+++ head/usr.bin/units/units.c
@@ -731,21 +731,21 @@
usage(void)
{
fprintf(stderr,
- "usage: units [-f unitsfile] [-H historyfile] [-UVq] [from-unit to-unit]\n");
+ "usage: units [-ehqtUVv] [-f unitsfile] [-o format] [from to]\n");
exit(3);
}
static struct option longopts[] = {
- {"help", no_argument, NULL, 'h'},
{"exponential", no_argument, NULL, 'e'},
{"file", required_argument, NULL, 'f'},
{"history", required_argument, NULL, 'H'},
+ {"help", no_argument, NULL, 'h'},
{"output-format", required_argument, NULL, 'o'},
{"quiet", no_argument, NULL, 'q'},
{"terse", no_argument, NULL, 't'},
{"unitsfile", no_argument, NULL, 'U'},
- {"verbose", no_argument, NULL, 'v'},
{"version", no_argument, NULL, 'V'},
+ {"verbose", no_argument, NULL, 'v'},
{ 0, 0, 0, 0 }
};

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