Command-line Usage

xmldiff is both a command-line tool and a Python library. To use it from the command-line, just run xmldiff with two input files:

$ xmldiff file1.xml file2.xml

There are a few extra options to modify the output, but be aware that not all of the combinations are meaningful, so don’t be surprised of you add one and nothing happens.



You can select different output formats with xmldiff, but beware that some formatters may assume certain things about the type of XML.

The included formatters are generic and will work for any type of XML, but may not give you a useful output. If you are using xmldiff as a library, you can create your own formatters that is suited for your particular usage of XML.

The diff formatter is default and will output a list of edit actions. The xml formatter will output XML with differences marked up by tags using the diff namespace. The old formatter is a formatter that gives a list of edit actions in a format similar to xmldiff 0.6 or 1.0.

Whitespace Handling

Formatters are also responsable for whitespace handling, both in parsing and in output.

By default xmldiff will strip all whitespace that is between tags, as opposed to inside tags. That whitespace isn’t a part of any data and can be ignored. So this XML structure:

<data count="1"></data><data count="2"></data>

Will be seen as the same document as this:

<data count="1"></data>    <data count="2"></data>

Because the whitespace is between the tags. However, this structure is different, since the whitespace there occurs inside a tag:

<data count="1">    </data><data count="2"></data>

By default the xml formatter will normalize this whitespace. You can turn that off with the --keep-whitespace argument.

Pretty Printing

The term “pretty printing” refers to making an output a bit more human readable by structuring it with whitespace. In the case of XML this means inserting ignorable whitespace into the XML, yes, the same in-between whitespace that is ignored by xmldiff when detecting changes between two files.

xmldiff’s xml formatter understands the --pretty-print argument and will insert whitespace to make the output more readable.

For example, an XML output that would normally look like this:

<document><story>Some content</story><story><para>This is some simple text with <i>formatting</i>.</para></story></document>

Will with the --pretty-print argument look like this:

  <story>Some content</story>
    <para>This is some simple text with <i>formatting</i>.</para>

This means you can actually use xmldiff to reformat XML, by using the xml formatter and passing in the same XML file twice:

$ xmldiff -f xml -p uglyfile.xml uglyfile.xml

However, if you keep whitespace with --keep-whitespace or -w, no reformatting will be done.