update-fonts-dir

update-fonts-dir [-v] [-i] [directory]

-v
    Verbose mode: prints each font file as it's scanned.

-i
    Ignore silently errors during processing font file.

directory
    The directory containing font files to process. If omitted, the current working directory is used.

The update-fonts-dir command creates or updates the fonts.dir file in a directory containing font files. This file contains a list of the font files in the directory and information about each font, such as its font name and encoding. This information is used by applications to quickly locate and load fonts. Running this command whenever new fonts are added or removed is crucial to ensure that X Window System applications can correctly display fonts. It works by scanning all the font files in the specified directory (or the current directory if none is specified), extracting the necessary font information, and writing it to the fonts.dir file.

Without an up-to-date fonts.dir file, applications may fail to recognize newly installed fonts, display garbled characters, or be unable to find existing fonts. This utility ensures that applications relying on the X Window System's font mechanism have accurate and current information about the fonts available on the system.

The command only affects font files within the specified directory. It doesn't recursively search subdirectories. Modern systems utilize fontconfig, which provides a more advanced font management system. While update-fonts-dir may still be useful in specific scenarios, it's often superseded by fontconfig-related tools.

The utility reads font files (e.g., .pcf, .pfa, .pfb) in a directory and creates or updates a fonts.dir file. This file maps font filenames to font descriptions, enabling applications to quickly access font information without parsing each font file every time. The first line in fonts.dir is the number of font entries in the directory, followed by the font filenames and their associated XLFD (X Logical Font Description) strings.

fc-cache(1)