Linux Commands Examples

A great documentation place for Linux commands


command line XML tool


xmllint [--version --debug --shell --debugent --copy --recover --noent --noout --nonet --path "PATH(S)" --load-trace --htmlout --nowrap --valid --postvalid --dtdvalid URL --dtdvalidfpi FPI --timing --output FILE --repeat --insert --compress --html --xmlout --push --memory --maxmem NBBYTES --nowarning --noblanks --nocdata --format --encode ENCODING --dropdtd --nsclean --testIO --catalogs --nocatalogs --auto --xinclude --noxincludenode --loaddtd --dtdattr --stream --walker --pattern PATTERNVALUE --chkregister --relaxng SCHEMA --schema SCHEMA --c14n] {XML-FILE(S)... -}

xmllint --help

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xmllint --format ugly.xml >pretty.xml
xmllint --noout --schema TDL.xsd "$1"
cat $1 | xmllint --format -
exec xmllint --format -
exec xmllint --format "$@"


The xmllint program parses one or more XML files, specified on the command line as XML-FILE (or the standard input if the filename provided is - ). It prints various types of output, depending upon the options selected. It is useful for detecting errors both in XML code and in the XML parser itself.

xmllint is included in libxml(3).


xmllint accepts the following options (in alphabetical order):


Generate a small document for testing purposes.


Use the SGML catalog(s) from SGML_CATALOG_FILES. Otherwise XML catalogs starting from /etc/xml/catalog are used by default.


Turn on node registration. Useful for developers testing libxml(3) node tracking code.


Turn on gzip(1) compression of output.


Test the internal copy implementation.


Use the W3C XML Canonicalisation (C14N) to serialize the result of parsing to stdout. It keeps comments in the result.

--dtdvalid URL

Use the DTD specified by an URL for validation.

--dtdvalidfpi FPI

Use the DTD specified by a Formal Public Identifier FPI for validation, note that this will require a catalog exporting that Formal Public Identifier to work.


Parse a file and output an annotated tree of the in-memory version of the document.


Debug the entities defined in the document.


Remove DTD from output.


Fetch external DTD and populate the tree with inherited attributes.

--encode ENCODING

Output in the given encoding.


Reformat and reindent the output. The XMLLINT_INDENT environment variable controls the indentation. The default value is two spaces " ").


Print out a short usage summary for xmllint.


Use the HTML parser.


Output results as an HTML file. This causes xmllint to output the necessary HTML tags surrounding the result tree output so the results can be displayed/viewed in a browser.


Test for valid insertions.


Fetch an external DTD.


Display all the documents loaded during the processing to stderr.

--maxmem NNBYTES

Test the parser memory support. NNBYTES is the maximum number of bytes the library is allowed to allocate. This can also be used to make sure batch processing of XML files will not exhaust the virtual memory of the server running them.


Parse from memory.


Drop ignorable blank spaces.


Do not use any catalogs.


Substitute CDATA section by equivalent text nodes.


Substitute entity values for entity references. By default, xmllint leaves entity references in place.


Do not use the Internet to fetch DTDs or entities.


Suppress output. By default, xmllint outputs the result tree.


Do not emit warnings from the parser and/or validator.


Do not output HTML doc wrapper.


Do XInclude processing but do not generate XInclude start and end nodes.


Remove redundant namespace declarations.

--output FILE

Define a file path where xmllint will save the result of parsing. Usually the programs build a tree and save it on stdout, with this option the result XML instance will be saved onto a file.

--path "PATH(S)"

Use the (space- or colon-separated) list of filesystem paths specified by PATHS to load DTDs or entities. Enclose space-separated lists by quotation marks.


Used to exercise the pattern recognition engine, which can be used with the reader interface to the parser. It allows to select some nodes in the document based on an XPath (subset) expression. Used for debugging.


Validate after parsing has completed.


Use the push mode of the parser.


Output any parsable portions of an invalid document.

--relaxng SCHEMA

Use RelaxNG file named SCHEMA for validation.


Repeat 100 times, for timing or profiling.

--schema SCHEMA

Use a W3C XML Schema file named SCHEMA for validation.


Run a navigating shell. Details on available commands in shell mode are below (see the section called “SHELL COMMANDS”).


Use streaming API - useful when used in combination with --relaxng or --valid options for validation of files that are too large to be held in memory.


Test user input/output support.


Output information about the time it takes xmllint to perform the various steps.


Determine if the document is a valid instance of the included Document Type Definition (DTD). A DTD to be validated against also can be specified at the command line using the --dtdvalid option. By default, xmllint also checks to determine if the document is well-formed.


Display the version of libxml(3) used.


Test the walker module, which is a reader interface but for a document tree, instead of using the reader API on an unparsed document it works on an existing in-memory tree. Used for debugging.


Do XInclude processing.


Used in conjunction with --html. Usually when HTML is parsed the document is saved with the HTML serializer. But with this option the resulting document is saved with the XML serializer. This is primarily used to generate XHTML from HTML input.


xmllint return codes provide information that can be used when calling it from scripts.


No error




Error in DTD


Validation error


Validation error


Error in schema compilation


Error writing output


Error in pattern (generated when --pattern option is used)


Error in Reader registration (generated when --chkregister option is used)


Out of memory error



SGML catalog behavior can be changed by redirecting queries to the user’s own set of catalogs. This can be done by setting the SGML_CATALOG_FILES environment variable to a list of catalogs. An empty one should deactivate loading the default /etc/sgml/catalog catalog.


XML catalog behavior can be changed by redirecting queries to the user’s own set of catalogs. This can be done by setting the XML_CATALOG_FILES environment variable to a list of catalogs. An empty one should deactivate loading the default /etc/xml/catalog catalog.


Setting the environment variable XML_DEBUG_CATALOG to non-zero using the export command outputs debugging information related to catalog operations.


Setting the environment variable XMLLINT_INDENT controls the indentation. The default value is two spaces " ".

shell commands

xmllint offers an interactive shell mode invoked with the --shell command. Available commands in shell mode include (in alphabetical order):


Display XML base of the node.


Leave the shell.

cat NODE

Display the given node or the current one.


Change the current node to the given path (if unique) or root if no argument is given.

dir PATH

Dumps information about the node (namespace, attributes, content).


Show the structure of the subtree under the given path or the current node.


Leave the shell.


Show this help.


Display memory usage.


Load a new document with the given filename.


List contents of the given path or the current directory.


Display the path to the current node.


Leave the shell.


Save the current document to the given filename or to the original name.


Check the document for errors.


Write the current node to the given filename.

see also


More information can be found at

libxml web page

W3C XSLT page


John Fleck <jfleck[:at:]inkstain[:dot:]net>, Ziying Sherwin <sherwin[:at:]nlm.nih[:dot:]gov>, Heiko Rupp <hwr[:at:]pilhuhn[:dot:]de>.

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