---
name: "fmtutil.cnf"
section: "5"
platform: "linux"
package: "texlive-doc"
version: "2026.1-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/fmtutil.cnf"
---

# fmtutil.cnf(5)

configuration file for fmtutil

## NAME

fmtutil.cnf - configuration file for fmtutil

## DESCRIPTION

The *fmtutil.cnf* file contains the configuration information for [**fmtutil**(8)](/fmtutil/8.md).  Each line contains the name of the format (e.g., \`\`tex´´, \`\`latex´´, \`\`omega´´), the name of the engine that is used by that format (e.g., \`\`tex´´, \`\`etex´´, \`\`omega´´), the pattern file (e.g., *language.dat*, *language.def*), and any arguments (name of an *.ini* file).

Fields are separated by whitespace and complete lines can be commented out with \`\`#´´.  The \`\`pattern file´´ field cannot be used to define a file that is used while building the format. It tells **fmtutil** which files (separated by commas) the format creation procedure reads and it has an effect to the options *--showhyphen* and *--byhyphen*. If the format has no way to customize hyphenation, a \`\`-´´ can be used to indicate this.

## NOTES

The [**tex**(1)](/tex/1.md) and [**amstex**(1)](/amstex/1.md) formats always load *hyphen.tex*.  No customization by a pattern file is available for these formats. Therefore, the pattern-file field for the **tex** and **amstex** is usually indicated to be empty (\`\`-´´).

You can, however, build customized formats on top of plain [**tex**(1)](/tex/1.md) or [**amstex**(1)](/amstex/1.md) by using *bplain.tex* instead of *plain.tex* (b for the *Babel* system). See, for example, the *bplain.ini* file for the bplain format).

[**etex**(1)](/etex/1.md) loads *language.def*, not *language.dat*.

Symbolic links to the correct engines (e.g., bplain -\> tex) are generated by the [**texlinks**(8)](/texlinks/8.md) script.  Remember to run [**texlinks**(8)](/texlinks/8.md) if you run [**fmtutil**(8)](/fmtutil/8.md) yourself, rather than using the FORMATS option in **texconfig**(8).

## FILES

- *fmtutil.cnf*

  default configuration file

- *language.dat*

  hyphenation pattern file

- *language.def*

  hyphenation pattern file

- *language.dat.lua*

  hyphenation pattern file

## SEE ALSO

[**amstex**(1)](/amstex/1.md), [**etex**(1)](/etex/1.md), [**fmtutil**(8)](/fmtutil/8.md), [**tex**(1)](/tex/1.md), **texconfig**(8), [**texlinks**(8)](/texlinks/8.md).

\<https://tug.org/texlive/scripts-sys-user.html\>

## BUGS

Email bug reports to \<https://lists.tug.org/tex-k\> (public mailing list).

## AUTHOR

**fmtutil** and *fmtutil.cnf* was originally written by Thomas Esser.

This manual page was written by C.M. Connelly for the Debian GNU/Linux system. It is now maintained as part of TeX Live.