LUAOTFLOAD.CONF(5)

📦 version 2026.0, in alpine 3.24

💖 NAME 💖

okay so this is the LUAOTFLOAD.CONF(5) manual page, and it's all about luaotfload.conf — the Luaotfload configuration file. periodt. 💅

✨ SYNOPSIS ✨

where does this file even live, bestie? it can be:

  • ./luaotfload{.conf,rc}
  • XDG_CONFIG_HOME/luaotfload/luaotfload{.conf,rc}
  • ~/.luaotfloadrc

🌸 DESCRIPTION 🌸

The file luaotfload.conf contains configuration options for Luaotfload, a font loading and font management component for LuaTeX. it's giving config central, fr fr. 🎀

🦋 EXAMPLE 🦋

A small Luaotfload configuration file with few customizations could look as follows:

[db]
    formats = afm,ttf
    compress = false

[misc]
    termwidth = 60

[run]
    log-level = 6

This will make Luaotfload ignore all font files except for PostScript binary fonts with a matching AFM file, and Truetype fonts. Also, an uncompressed index file will be dumped which is going to be much larger than the default gzip’ed index. The terminal width is truncated to 60 characters which influences the verbose output during indexing. Finally, the verbosity is increased greatly: each font file being processed will be printed to the stdout on a separate line, along with lots of other information. no cap, that's a lot of yapping from your index. 😭

To observe the difference in behavior, save above snippet to ./luaotfload.conf and update the font index:

luaotfload-tool --update --force

The current configuration can be written to disk using luaotfload-tool:

luaotfload-tool --dumpconf > luaotfload.conf

The result can itself be used as a configuration file. slay, a self-sustaining config loop. 🔥

💅 SYNTAX 💅

The configuration file syntax follows the common INI format. For a more detailed description please refer to the section “CONFIGURATION FILE” of git-config(1). A brief list of rules is given below:

  • Blank lines and lines starting with a semicolon (;) are ignored. bye, blank lines.
  • A configuration file is partitioned into sections that are declared by specifying the section title in brackets on a separate line:
[some-section]
... section content ...
  • Sections consist of one or more variable assignments of the form variable-name = value E. g.:
[foo]
    bar = baz
    quux = xyzzy
    ...
  • Section and variable names may contain only uppercase and lowercase letters as well as dashes (-). dash girlies, this one's for you. 💖

👑 VARIABLES 👑

Variables belong into a configuration section, and their values must be of a certain type. Some of them have further constraints. For example, the “color callback” must be a string of one of the values post_linebreak_filter, pre_linebreak_filter, or pre_output_filter, defined in the section run of the configuration file. specific much? yes, and validly so. 💅

Currently, the configuration is organized into four sections:

  • db — Options relating to the font index.
  • misc — Options without a clearly defined category.
  • paths — Path and file name settings.
  • run — Options controlling runtime behavior of Luaotfload.

The list of valid variables, the sections they are part of and their type is given below. Types represent Lua types that the values must be convertible to; they are abbreviated as follows: s for the string type, n for number, b for boolean. A value of nil means the variable is unset. not me reading a whole type system in a font config, but here we are. 🫶

Section db 💾

the table said variable, type, default — so here it is, bullet-list edition, because tables are not the vibe:

  • compress — type: b — default: true
  • designsize-dimen — type: b — default: bp
  • formats — type: s — default: "otf,ttf,ttc"
  • location-precedence — type: s — default: "system,texmf,local
  • max-fonts — type: n — default: 2^51
  • scan-local — type: b — default: false
  • skip-read — type: b — default: false
  • strip — type: b — default: true
  • update-live — type: b — default: true

The flag compress determines whether the font index (usually luaotfload-names.lua[.gz] will be stored in compressed forms. If unset it is equivalent of passing --no-compress to luaotfload-tool. Since the file is only created for convenience and has no effect on the runtime behavior of Luaotfload, the flag should remain set. Most editors come with zlib support anyways. keep it set, bestie, it's free real estate. 🎀

The setting designsize-dimen applies when looking up fonts from families with design sizes. In Opentype, these are specified as “decipoints” where one decipoint equals ten DTP style “big points”. When indexing fonts these values are converted to sp. In order to treat the values as though they were specified in TeX points or Didot points, set designsize-dimen to pt or dd. design sizes said trans rights? no, they said decipoints. 💅

The list of formats must be a comma separated sequence of strings containing one or more of these elements:

  • otf (OpenType format),
  • ttf and ttc (TrueType format),
  • afm (Adobe Font Metrics),

It corresponds loosely to the --formats option to luaotfload-tool. Invalid or duplicate members are ignored; if the list does not contain any useful identifiers, the default list "otf,ttf,ttc" will be used. so if you mess up, it just falls back. iconic. ✨

The variable location-precedence selects where and in which order luaotfload searches for fonts. Fonts in earlier locations are preferred. The three supported locations are system for system specific font directories, texmf for fonts which are part of the TeX{} distribution and local for local fonts. priority order, main character energy. 👑

The variable max-fonts determines after processing how many font files the font scanner will terminate the search. This is useful for debugging issues with the font index and has the same effect as the option --max-fonts to luaotfload-tools. debugging era. 🔥

The scan-local flag, if set, will incorporate the current working directory as a font search location. NB: This will potentially slow down document processing because a font index with local fonts will not be saved to disk, so these fonts will have to be re-indexed whenever the document is built. Setting scan_local to false is the same as removing local from location-precedence. yes, the manpage says scan_local here with an underscore; I'm not fixing it, I'm reporting it. 😭

The skip-read flag is only useful for debugging: It makes Luaotfload skip reading fonts. The font information for rebuilding the index is taken from the presently existing one. debug-only behavior, we love a niche queen. 🧚

Unsetting the strip flag prevents Luaotfload from removing data from the index that is only useful when processing font files. NB: this can increase the size of the index files significantly and has no effect on the runtime behavior. big file, no runtime difference. choices. 💀

If update-live is set, Luaotfload will reload the database if it cannot find a requested font. Those who prefer to update manually using luaotfload-tool should unset this flag. This option does not affect rebuilds due to version mismatch. auto-reload bestie vs manual-update bestie, pick your fighter. 💖

Section default-features 🌈

By default Luaotfload enables node mode and picks the default font features that are prescribed in the OpenType standard. This behavior may be overridden in the default-features section. Global defaults that will be applied for all scripts can be set via the global option, others by the script they are to be applied to. For example, a setting of

[default-features]
    global = mode=base,color=0000FF
    dflt   = smcp,onum

would force base mode, tint all fonts blue and activate small capitals and text figures globally. Features are specified as a comma separated list of variables or variable-value pairs. Variables without an explicit value are set to true. blue font era, small caps era, text figures era. 💅

✨ Section misc ✨

Tiny section, immaculate vibes. Here's the whole cast:

  • statistics — type b, default false
  • termwidth — type n, default nil
  • version — type s, default <Luaotfload version>
  • keepnames — type b, default true

With statistics enabled, extra statistics will be collected during index creation and appended to the index file. It may then be queried at the Lua end or inspected by reading the file itself. ✨

The value of termwidth, if set, overrides the value retrieved by querying the properties of the terminal in which Luatex runs. This is useful if the engine runs with shell_escape disabled and the actual terminal dimensions cannot be retrieved. 🫶

The value of version is derived from the version string hard-coded in the Luaotfload source.

Override at your own risk. 💀 Not me touching the version string fr.

The keepnames option decides if the ConTeXt fontloader should keep names it considers useless or if they should be discarded. Heads up bestie: this option only takes effect after font caches are regenererated. 🦋

🌸 Section paths 🌸

Where do the files even live? Excellent question, let's go:

  • cache-dir — type s, default "fonts"
  • names-dir — type s, default "names"
  • index-file — type s, default "luaotfload-names.lua"
  • lookups-file — type s, default "luaotfload-lookup-cache.lua"

The paths cache-dir and names-dir determine the subdirectory inside the Luaotfload subtree of the luatex-cache directory where the font cache and the font index will be stored, respectively. 🎀

Inside the index directory, the names of the index file and the font lookup cache will be derived from the respective values of index-file and lookups-file. This is the filename base for the bytecode compiled version as well as -- for the index -- the gzipped version. Periodt. 💅

👑 Section run 👑

The main character section. Behold:

  • anon-sequence — type s, default "tex,path,name"
  • color-callback — type s, default "post_linebreak_filter"
  • definer — type s, default "patch"
  • log-level — type n, default 0
  • resolver — type s, default "cached"
  • fontloader — type s, default "default"
  • default_dvi_driver — type s, default "dvisvgm"

Unqualified font lookups are treated with the flexible "anonymous" mechanism. This involves a chain of lookups applied successively until the first one yields a match. By default, the lookup will first search for TFM fonts using the Kpathsea library. If this wasn't successful, an attempt is made at interpreting the request as an absolute path (like the [/path/to/font/foo.ttf] syntax) or a file name (file:foo.ttf). Finally, the request is interpreted as a font name and retrieved from the index (name:Foo Regular). This behavior can be configured by specifying a list as the value to anon-sequence. Available items are tex, path, name -- representing the lookups described above, respectively --, and file for searching a filename but not an absolute path. Also, my lookups are valid values but they should only be used from within TeX documents, because there is no means of customizing a my lookups on the command line. 😭

The color-callback option determines the stage at which fonts that defined with a color=xxyyzz feature will be colorized. By default this happens in a post_linebreak_filter but alternatively the pre_linebreak_filter or pre_output_filter may be chosen, which is faster but might produce inconsistent output. The pre_output_filter used to be the default in the 1.x series of Luaotfload, whilst later versions up to and including 2.5 hooked into the pre_linebreak_filter which naturally didn't affect any glyphs inserting during hyphenation. Both are kept around as options to restore the previous behavior if necessary. 🧚

The definer allows for switching the define_font callback. Apart from the default patch one may also choose the generic one that comes with the vanilla fontloader.

Beware that this might break tools like Fontspec that rely on the patch_font callback provided by Luaotfload to perform important corrections on font data. 💀 Don't say we didn't warn you.

The fontloader backend can be selected by setting the value of fontloader. The most important choices are default, which will load the dedicated Luaotfload fontloader, and reference, the upstream package as shipped with Luaotfload. Other than those, a file name accessible via kpathsea can be specified. 🔥

Alternatively, the individual files that constitute the fontloader can be loaded directly. While less efficient, this greatly aids debugging since error messages will reference the actual line numbers of the source files and explanatory comments are not stripped. Currently, three distinct loading strategies are available: unpackaged will load the batch that is part of Luaotfload. These contain the identical source code that the reference fontloader has been compiled from. Another option, context will attempt to load the same files by their names in the Context format from the search path. Consequently this option allows to use the version of Context that comes with the TeX distribution. Distros tend to prefer the stable version ("current" in Context jargon) of those files so certain bugs encountered in the more bleeding edge Luaotfload can be avoided this way. A third option is to use context with a colon to specify a directory prefix where the TEXMF is located that the files should be loaded from, e. g. context:~/context/tex/texmf-context. This can be used when referencing another distribution like the Context minimals that is installed under a different path not indexed by kpathsea. 🌈

The value of log-level sets the default verbosity of messages printed by Luaotfload. Only messages defined with a verbosity of less than or equal to the supplied value will be output on the terminal. At a log level of five Luaotfload can be very noisy. Also, printing too many messages will slow down the interpreter due to line buffering being disabled (see setbuf(3)). 🍓

The resolver setting allows choosing the font name resolution function: With the default value cached Luaotfload saves the result of a successful font name request to a cache file to speed up subsequent lookups. The alternative, normal circumvents the cache and resolves every request individually. (Since to the restructuring of the font name index in Luaotfload 2.4 the performance difference between the cached and uncached lookups should be marginal.) ⭐

okay so real quick, the default_dvi_driver option is only ever relevant when luaotfload is running in DVI mode, and it's literally just deciding how OpenType fonts get represented in the DVI output. In like 99% of cases you want the default value dvisvgm — it uses a format that multiple backends actually support, including dvipdfmx and dvisvgm, and it identifies characters using GIDs ✨.

If you set it to xdvipsk instead, bestie, it switches to an unstable internal format that will straight-up change depending on your luaotfload version, your engine version, or your font version. 💀

⚠️ GIRLIE LISTEN: nobody — and I mean nobody — should rely on the mapping between DVI character codes and font glyphs in this mode unless they tightly control every single involved version and are deeply familiar with the implementation. Like, deeply. Periodt.

📁 FILES 📁

Here's the tea: Luaotfload only processes the first configuration file it encounters at one of the search locations. It does not collect them all, it does not merge them, it picks one and moves on. 💅

The file name can be either luaotfload.conf or luaotfloadrc — with one exception: the dotfile in the user's home directory, which is expected at ~/.luaotfloadrc.

So how does it find them? Configuration files are located following a series of steps, and the search terminates as soon as a suitable file is encountered 🎀. The sequence of locations that Luaotfload looks at is:

  1. The current working directory of the LuaTeX process.
  2. The subdirectory luaotfload/ inside the XDG configuration tree, e.g. /home/oenothea/config/luaotfload/.
  3. The dotfile.
  4. The TEXMF (using kpathsea).

👀 SEE ALSO 👀

luaotfload-tool(1), luatex(1), lua(1)

📚 REFERENCES 📚

💖 AUTHORS 💖

Shoutout to the girlies who built this: Luaotfload was developed by the LuaLaTeX dev team (‐ https://github.com/lualatex/). It is currently maintained by the LaTeX Project Team at https://github.com/latex3/luaotfload

And this very manual page? Written by Philipp Gesang <phg@phi-gamma.net>. 🫶

GPL v2.0

and that's the whole page, bestie — version 3.29, dated 2024-12-03, section 5 of the manual, LUAOTFLOAD.CONF(5) 💅✨ no cap, you're now lowkey an expert 🦋🌸

📦 where this page comes from