How to Pretty-Print XML From Command Line?

XML is a commonly used format for exchanging data between systems. It is used extensively in web applications and other areas where data needs to be exchanged between different systems. However, XML can be difficult to read and understand when it is in its raw format. Pretty-printing XML is process of formatting XML in a more readable and understandable way. This article will discuss how to pretty-print XML from command line.

What is Pretty-Printing?

Pretty-printing is process of formatting data in a more human-readable and understandable way. In case of XML, pretty-printing involves adding whitespace and line breaks to XML to make it more readable. This makes it easier for humans to read and understand XML code.

Why Pretty-Print XML?

There are several reasons why you might want to pretty-print XML. First, pretty-printing makes XML easier to read and understand. When XML is in its raw format, it can be difficult to understand structure of data. Pretty-printing adds whitespace and line breaks to XML, making it easier to read and understand.

Second, pretty-printing can help with debugging. If you are working with XML and encounter an error, pretty-printing can make it easier to identify source of error. When XML is pretty-printed, errors in structure of XML are often easier to identify.

Third, pretty-printing can help with version control. When XML is pretty-printed, it is easier to see differences between different versions of XML. This can be helpful when tracking changes to XML over time.

How to Pretty-Print XML from Command Line

There are several tools available for pretty-printing XML from command line. In this article, we will discuss three popular tools: xmllint, xmlstarlet, and tidy.

xmllint

xmllint is a command-line tool that is part of libxml2 library. It is available on most Linux and Unix systems, and can be installed on Windows using Cygwin. xmllint can be used to validate XML documents as well as pretty-print them.

To pretty-print an XML file using xmllint, use following command −

xmllint --format input.xml

This will pretty-print XML file and output result to console. If you want to save result to a file, you can use following command −

xmllint --format input.xml > output.xml

This will save pretty-printed XML to a file named output.xml.

xmlstarlet

xmlstarlet is a command-line tool for processing XML data. It can be used to pretty-print XML as well as perform other tasks such as selecting nodes, updating values, and transforming XML data. xmlstarlet is available on most Linux and Unix systems, and can be installed on Windows using Cygwin.

To pretty-print an XML file using xmlstarlet, use following command −

xmlstarlet fo input.xml

This will pretty-print XML file and output result to console. If you want to save result to a file, you can use following command −

xmlstarlet fo input.xml > output.xml

This will save pretty-printed XML to a file named output.xml.

tidy

tidy is a command-line tool for cleaning up HTML and XML documents. It can be used to pretty-print XML as well as perform other tasks such as fixing errors and cleaning up formatting. tidy is available on most Linux and Unix systems, and can be installed on Windows using Cygwin.

To pretty-print an XML file using tidy, use following command −

tidy -xml -i input.xml
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This will pretty-print XML file and output result to console. If you want to save result to a file, you can use following command −

tidy -xml -i input.xml > output.xml

This will save pretty-printed XML to a file named output.xml.

Comparison of Pretty-Printing Tools

Each of pretty-printing tools discussed above has its own strengths and weaknesses. xmllint is a simple and reliable tool that is available on most systems, but it can be slow for large XML files. xmlstarlet is a powerful tool that can perform many different tasks, but it can be more difficult to use than xmllint. tidy is a tool for cleaning up HTML and XML, and while it can be used for pretty-printing, it may not be best choice for large or complex XML files.

Here is a comparison of three tools −

Tool	Pros	Cons
xmllint	Simple and reliable, available on most systems	Can be slow for large XML files
xmlstarlet	Powerful and versatile, can perform many different tasks	More difficult to use than xmllint
tidy	Can be used for pretty-printing as well as cleaning up HTML/XML	May not be best choice for large or complex XML files

Additional Techniques for Pretty-Printing XML

In addition to command-line tools discussed above, there are other techniques that can be used to pretty-print XML. Here are a few additional techniques −

Online Tools

There are several online tools available for pretty-printing XML. These tools allow you to upload an XML file and then download a pretty-printed version of file. Some popular online tools include XML Formatter, XML Beautifier, and Online XML Pretty Print.

While online tools can be convenient, they may not be suitable for sensitive data or files with large sizes, as upload/download process can take a lot of time.

Integrated Development Environments (IDEs)

Many integrated development environments (IDEs) have built-in support for pretty-printing XML. For example, in Eclipse, you can pretty-print XML by selecting XML file and choosing "Format" from context menu. Other IDEs, such as Visual Studio Code and IntelliJ IDEA, also have built-in support for pretty-printing XML.

Using an IDE for pretty-printing XML can be convenient if you are already working in an IDE, but may not be practical if you are working on a remote server or using a different text editor.

Text Editors

Some text editors, such as Sublime Text and Atom, have plugins or packages available for pretty-printing XML. These plugins allow you to pretty-print XML directly within text editor, without needing to switch to a command-line tool or online tool.

Using a text editor for pretty-printing XML can be convenient if you are already using text editor for other tasks, but may not be as feature-rich as some of command-line tools or IDEs.

Tips for Pretty-Printing XML

Here are a few tips for pretty-printing XML −

Use Consistent Indentation

When pretty-printing XML, it is important to use consistent indentation. This makes it easier to read and understand structure of XML. Most pretty-printing tools will automatically add indentation, but you may need to adjust settings to ensure that indentation is consistent.

Remove Unnecessary Whitespace

While it is important to add whitespace to make XML more readable, it is also important to remove unnecessary whitespace. This can help to reduce size of XML file and make it easier to work with. Most pretty-printing tools will remove unnecessary whitespace by default, but you may need to adjust settings to ensure that this is happening.

Use Line Breaks to Separate Elements

In addition to indentation, it can be helpful to use line breaks to separate elements in XML. This can make it easier to see where one element ends and another begins. Most pretty-printing tools will add line breaks automatically, but you may need to adjust settings to ensure that line breaks are consistent.

Conclusion

Pretty-printing XML is an important task for making XML data more readable and understandable. There are several tools available for pretty-printing XML from command line, including xmllint, xmlstarlet, and tidy. Each tool has its own strengths and weaknesses, so it is important to choose tool that is best suited to your needs. With help of these tools, you can easily pretty-print XML and make it more readable and understandable for humans.