xmllint:tldr:ac6c8

The command xmllint --valid ${source_file-xml} is used to execute the xmllint program with the --valid option and a specified source file.

Here's a breakdown of each component of the command:

• xmllint: It is a command-line tool for parsing and validating XML documents.
• --valid: It is an option for xmllint that performs a validation check on the provided XML file.
• ${source_file-xml}: It represents a variable called source_file, which is the name of the XML file to be validated. The ${source_file-xml} syntax means that if the source_file variable is not defined, it will default to "xml".

To use this command, replace ${source_file-xml} with the actual name and location of the XML file you want to validate.