: Variations are set globally. The format for specifying variation settings follows. All valid CSS font-variation-settings values other than 'normal' and 'inherited' are also accepted, though, not documented below.
: The format is a tag, optionally followed by an equals sign, followed by a number. For example:
: "wght=500" "slnt=-7.5"

Text options:

If no text is provided, standard input is used for input.

Textual context options:

--text-before=string: Set text context before each line
--text-after=string: Set text context after each line
--unicodes-before=list of hex numbers: Set Unicode codepoints context before each line
--unicodes-after=list of hex numbers: Set Unicode codepoints context after each line

Shape options:

--list-shapers: List available shapers and quit
--direction=ltr/rtl/ttb/btt: Set text direction (default: auto)
--language=BCP 47 tag: Set text language (default: $LANG)
--script=ISO-15924 tag: Set text script (default: auto)
--bot: Treat text as beginning-of-paragraph
--eot: Treat text as end-of-paragraph
--preserve-default-ignorables: Preserve Default-Ignorable characters
--remove-default-ignorables: Remove Default-Ignorable characters
--invisible-glyph: Glyph value to replace Default-Ignorables with
--not-found-glyph: Glyph value to replace not-found characters with
--not-found-variation-selector-glyph: Glyph value to replace not-found variation-selector characters with
--utf8-clusters: Use UTF8 byte indices, not char indices
--cluster-level=0/1/2/3: Cluster merging level (default: 0)
--normalize-glyphs: Rearrange glyph clusters in nominal order
--unsafe-to-concat: Produce unsafe-to-concat glyph flag
--safe-to-insert-tatweel: Produce safe-to-insert-tatweel glyph flag
--glyphs: Interpret input as glyph string
--verify: Perform sanity checks on shaping results

: Features can be enabled or disabled, either globally or limited to specific character ranges. The format for specifying feature settings follows. All valid CSS font-feature-settings values other than 'normal' and the global values are also accepted, though not documented below. CSS string escapes are not supported. The range indices refer to the positions between Unicode characters, unless the --utf8-clusters is provided, in which case range indices refer to UTF-8 byte indices. The position before the first character is always 0.

: text: [<glyph name or index>=<glyph cluster index within input>@<horizontal displacement>,<vertical displacement>+<horizontal advance>,<vertical advance>|...] json: [{"g": <glyph name or index>, "ax": <horizontal advance>, "ay": <vertical advance>, "dx": <horizontal displacement>, "dy": <vertical displacement>, "cl": <glyph cluster index within input>}, ...]

--show-text: Prefix each line of output with its corresponding input text
--show-unicode: Prefix each line of output with its corresponding input codepoint(s)
--show-line-num: Prefix each line of output with its corresponding input line number
-v, --verbose: Prefix each line of output with all of the above
--no-glyph-names: Output glyph indices instead of names
--no-positions: Do not output glyph positions
--no-advances: Do not output glyph advances
--no-clusters: Do not output cluster indices
--show-extents: Output glyph extents
--show-flags: Output glyph flags
--ned: No Extra Data; Do not output clusters or advances
-V, --trace: Output interim shaping results

Shows results of shaping text with a given font in textual or JSON format.