<program>hb-shape</program> allows you to run HarfBuzz's hb_shape() function on an input string and to examine the outcome, in human-readable form, as terminal output. <program>hb-shape</program> does not render the results of the shaping call into rendered text (you can use <program>hb-view</program>, below, for that). Instead, it prints out the final glyph indices and positions, taking all shaping operations into account, as if the input string were a HarfBuzz input buffer.

You can specify the font to be used for shaping and, with command-line options, you can add various aspects of the internal state to the output that is sent to the terminal. The general format is

	hb-shape [[OPTIONS]]
      path/to/font/file.ttf
      yourinputtext
      

The default output format is plain text (although JSON output can be selected instead by specifying the option [--output-format=json]). The default output syntax reports each glyph name (or glyph index if there is no name) followed by its cluster value, its horizontal and vertical position displacement, and its horizontal and vertical advances.

Output options exist to skip any of these elements in the output, and to include additional data, such as Unicode code-point values, glyph extents, glyph flags, or interim shaping results.

Output can also be redirected to a file, or input read from a file. Additional options enable you to enable or disable specific font features, to set variation-font axis values, to alter the language, script, direction, and clustering settings used, to enable sanity checks, or to change which shaping engine is used.

For a complete explanation of the options available, run

	hb-shape --help
      

<program>hb-view</program> allows you to see the shaped output of an input string in rendered form. Like <program>hb-shape</program>, <program>hb-view</program> takes a font file and a text string as its arguments:

	hb-view [[OPTIONS]]
	path/to/font/file.ttf
	yourinputtext
      

By default, <program>hb-view</program> renders the shaped text in ASCII block-character images as terminal output. By appending the --output-file=[filename] switch, you can write the output to a PNG, SVG, or PDF file (among other formats).

As with <program>hb-shape</program>, a lengthy set of options is available, with which you can enable or disable specific font features, set variation-font axis values, alter the language, script, direction, and clustering settings used, enable sanity checks, or change which shaping engine is used.

You can also set the foreground and background colors used for the output, independently control the width of all four margins, alter the line spacing, and annotate the output image with

In general, <program>hb-view</program> is a quick way to verify that the output of HarfBuzz's shaping operation looks correct for a given text-and-font combination, but you may want to use <program>hb-shape</program> to figure out exactly why something does not appear as expected.

<program>hb-subset</program> allows you to generate a subset of a given font, with a limited set of supported characters, features, and variation settings.

By default, you provide an input font and an input text string as the arguments to <program>hb-subset</program>, and it will generate a font that covers the input text exactly like the input font does, but includes no other characters or features.

	hb-subset [[OPTIONS]]
	path/to/font/file.ttf
	yourinputtext
      

For example, to create a subset of Noto Serif that just includes the numerals and the lowercase Latin alphabet, you could run

	hb-subset [[OPTIONS]]
	NotoSerif-Regular.ttf
	0123456789abcdefghijklmnopqrstuvwxyz
      

There are options available to remove hinting from the subsetted font and to specify a list of variation-axis settings.