Next: , Previous: Unit expressions, Up: Top



5 Invoking units

You invoke units like this:

         units [options] [from-unit [to-unit]]

If the from-unit and to-unit are omitted, then the program will use interactive prompts to determine which conversions to perform. See Interactive use. If both from-unit and to-unit are given, units will print the result of that single conversion and then exit. If only from-unit appears on the command line, units will display the definition of that unit and exit. Units specified on the command line will need to be quoted to protect them from shell interpretation and to group them into two arguments. See Command line use.

The following options allow you to read in an alternative units file, check your units file, or change the output format:

-c
--check
Check that all units and prefixes defined in the units data file reduce to primitive units. Print a list of all units that cannot be reduced. Also display some other diagnostics about suspicious definitions in the units data file. Note that only definitions active in the current locale are checked.
--check-verbose
Like the -check option, this option prints a list of units that cannot be reduced. But to help find unit definitions that cause endless loops, it lists the units as they are checked. If units hangs, then the last unit to be printed has a bad definition. Note that only definitions active in the current locale are checked.
-o format
--output-format format
Use the specified format for numeric output. Format is the same as that for the printf function in the ANSI C standard. For example, if you want more precision you might use -o %.15g.
-f filename
--file filename
Instruct units to load the units file filename. If filename is the empty string (-f '') then the default units file will be loaded. This enables you to load the default file plus a personal units file. Up to 25 units files may be specified on the command line. This option overrides the UNITSFILE environment variable.
-h
--help
Print out a summary of the options for units.
-m
--minus
Causes - to be interpreted as a subtraction operator. This is usually the default behavior.
-p
--product
Causes - to be interpreted as a multiplication operator when it has two operands. It will as a negation operator when it has only one operand: (-3). Note that by default - is treated as a subtraction operator.
-q
--quiet
--silent
Suppress prompting of the user for units and the display of statistics about the number of units loaded.
-s
--strict
Suppress conversion of units to their reciprocal units. For example, units will normally convert hertz to seconds because these units are reciprocals of each other. The strict option requires that units be strictly conformable to perform a conversion, and will give an error if you attempt to convert hertz to seconds.
-t
--terse
Give terse output when converting units. This option can be used when calling units from another program so that the output is easy to parse.
-v
--verbose
Give slightly more verbose output when converting units. When combined with the -c option this gives the same effect as --check-verbose.
-V
--version
Print program version number, tell whether the readline library has been included, and give the location of the default units data file.