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.