# Mimetypes management

## Mimetype aliases

Nextcloud allows you to create aliases for mimetypes, so that you can display custom icons for files. For example, you might want a nice audio icon for audio files instead of the default file icon.

By default Nextcloud is distributed with `nextcloud/resources/config/mimetypealiases.dist.json`. Do not modify this file, as it will be replaced when Nextcloud is updated. Instead, create your own `nextcloud/config/mimetypealiases.json` file with your custom aliases. Use the same syntax as in `nextcloud/resources/config/mimetypealiases.dist.json`.

Once you have made changes to your `mimetypealiases.json`, use the `occ` command to propagate the changes through the system. This example is for Ubuntu Linux:

    $ sudo -u www-data php occ maintenance:mimetype:update-js

See Using the occ command to learn more about `occ`.

Some common mimetypes that may be useful in creating aliases are:

image
  Generic image
image/vector
  Vector image
audio
  Generic audio file
x-office/document
  Word processed document
x-office/spreadsheet
  Spreadsheet
x-office/presentation
  Presentation
text
  Generic text document
text/code
  Source code

## Mimetype mapping

Nextcloud allows administrators to specify the mapping of a file extension to a mimetype. For example files ending in `mp3` map to `audio/mpeg`. Which then in turn allows Nextcloud to show the audio icon.

By default Nextcloud comes with `mimetypemapping.dist.json`. This is a simple json array. Administrators should not update this file as it will get replaced on upgrades of Nextcloud. Instead the file `mimetypemapping.json` should be created and modified, this file has precedence over the shipped file.

## Icon retrieval

When an icon is retrieved for a mimetype, if the full mimetype cannot be found, the search will fallback to looking for the part before the slash. Given a file with the mimetype ‘image/my-custom-image’, if no icon exists for the full mimetype, the icon for ‘image’ will be used instead. This allows specialised mimetypes to fallback to generic icons when the relevant icons are unavailable.

Read the Docs v: latest

Versions
  16
  17
  18
  stable
  latest

Downloads

On Read the Docs
  Project Home
  Builds

Free document hosting provided by Read the Docs.