fc-validate

fc-validate [options] fontfile1 [fontfile2 ...]

-v
    Enable verbose output showing the details of the font validation process.

-q
    Suppress all output, only returning an exit code indicating success or failure.

-s
    Validate all fonts in the system font directories.

fc-validate is a command-line tool provided by the Fontconfig library for validating font files. It checks font files for structural integrity and common errors, such as incorrect glyph outlines, missing characters, or other inconsistencies. This tool is invaluable for font developers and system administrators to ensure that fonts are properly formatted and will function correctly with applications using Fontconfig. It reads font files, parses their data structures, and reports any issues encountered. The output indicates whether the fonts are valid according to Fontconfig's expectations, aiding in identifying and resolving font-related problems that might cause display errors or application crashes. fc-validate supports various font formats and can validate multiple font files in a single invocation. The tool reports errors that need to be resolved to ensure proper font rendering.

The validation performed by fc-validate is not exhaustive and may not catch all possible font errors. It focuses primarily on issues that affect Fontconfig's ability to load and use fonts. Corrected fonts may still present rendering issues.

fc-validate returns 0 if all fonts are valid, and a non-zero value if any errors are found.

If fc-validate reports an error in a font file, you should report the issue to the font's author or vendor. If the problem involves font handling in general, report it to the Fontconfig developers.

fc-cache(1), fc-list(1), fc-match(1)