12 Output Styles

The output can be tweaked in various ways using command line options. With no options, the output looks like this

$ units
Currency exchange rates from FloatRates (USD base) on 2023-07-08
3612 units, 109 prefixes, 122 nonlinear units

You have: 23ft
You want: m
        * 7.0104
        / 0.14264521
You have: m
You want: ft;in
        3 ft + 3.3700787 in

This is arguably a bit cryptic; the --verbose option makes clear what the output means:

$ units --verbose
Currency exchange rates from FloatRates (USD base) on 2023-07-08
3612 units, 109 prefixes, 122 nonlinear units

You have: 23 ft
You want: m
        23 ft = 7.0104 m
        23 ft = (1 / 0.14264521) m
You have: meter
You want: ft;in
        meter = 3 ft + 3.3700787 in

The --quiet option suppresses the clutter displayed when units starts, as well as the prompts to the user. This option is enabled by default when you give units on the command line.

$ units --quiet
23 ft
m
        * 7.0104
        / 0.14264521

$ units 23ft m
        * 7.0104
        / 0.14264521

The remaining style options allow you to display only numerical values without the tab or the multiplication and division signs, or to display just a single line showing the forward conversion:

$ units --compact 23ft m
7.0104
0.14264521

$ units --compact m 'ft;in'
3;3.3700787

$ units --one-line 23ft m
        * 7.0104

$ units --one-line 23ft 1/m
        reciprocal conversion
        * 0.14264521

$ units --one-line 23ft kg
conformability error
        7.0104 m
        1 kg

Note that when converting to a unit list, the --compact option displays a semicolon separated list of results. Also be aware that the one-line option doesn’t live up to its name if you execute a reciprocal conversion or if you get a conformability error. The former case can be prevented using the --strict option, which suppresses reciprocal conversions. Similarly you can suppress unit list conversion using --nolists. It is impossible to prevent the three line error output.

$ units --compact --nolists m 'ft;in'
Error in 'ft;in': Parse error

$ units --one-line --strict 23ft 1/m

The various style options can be combined appropriately. The ultimate combination is the --terse option, which combines --strict, --quiet, --one-line, and --compact to produce the minimal output, just a single number for regular conversions and a semicolon separated list for conversion to unit lists. This will likely be the best choice for programs that want to call units and then process its result.

$ units --terse 23ft m
7.0104

$ units --terse m 'ft;in'
3;3.3700787

$ units --terse 23ft 1/m
conformability error
7.0104 m
1 / m

$ units --terse '1 mile'
1609.344 m

$ units --terse mile
5280 ft = 1609.344 m