Manual:$wgExternalDiffEngine

Content handlers and storage: $wgExternalDiffEngine
Name of the external diff engine to use.
Introduced in version:	1.6.0 (r12987)
Removed in version:	Still in use
Allowed values:	(string) or false
Default value:	false
Other settings: Alphabetical | By function

Details

Name of the external diff engine to use, or false to use the internal engine.

The possible values are:

• false - wikidiff2 if available, PHP implementation else.
• any other string is treated as a path to external diff executable, which is passed two file-path arguments.

The following values are no longer supported as of MW 1.32:

MediaWiki version:

≤ 1.32

• 'wikidiff2' - Wikimedia's fast difference engine implemented as a PHP/HHVM module.

The following values are no longer supported as of MW 1.27:

MediaWiki version:

≤ 1.27

• 'wikidiff' and 'wikidiff3' - treated as false for backwards compatibility.

The external engine should return HTML for a table row containing four columns (two 'marker/content' pairs). These can be collapsed into one for diff formats that don't require columns, e.g. <tr><td colspan="4"> … </td></tr>

This setting replaces $wgUseExternalDiffEngine .

Example

To display diffs in the format of the common GNU diff program, it is necessary to wrap that executable in a small script such as the following. This is needed both to get the required HTML wrapper, and also because diff returns non-zero when inputs don't match (which they generally don't for wiki changes).

• externaldiff.sh

  #!/bin/bash
  
  echo "<tr><td colspan=4><pre>"
  # @todo This should also escape HTML.
  diff "$1" "$2"
  DIFFRET=$?
  echo "</pre></td></tr>"
  
  if [[ $DIFFRET -eq 1 ]]; then
      exit 0
  else
      exit $DIFFRET
  fi
  

• LocalSettings.php

  $wgDiffEngine = 'external';
  $wgExternalDiffEngine = '/path/to/externaldiff.sh';
  

See also

• $wgDiffEngine