MAN page from Fedora 2 expat-1.95.7-1.1.x86_64.rpm
Updated: 24 January 2003Index
xmlwf - Determines if an XML document is well-formed
xmlwf [ -s] [ -n] [ -p] [ -x] [ -e encoding] [ -w] [ -d output-dir] [ -c] [ -m] [ -r] [ -t] [ -v] [ file ...]
xmlwf uses the Expat library todetermine if an XML document is well-formed. It isnon-validating.
If you do not specify any files on the command-line, and youhave a recent version of xmlwf, theinput file will be read from standard input.
A well-formed document must adhere to thefollowing rules:
- The file begins with an XML declaration. For instance,<?xml version="1.0" standalone="yes"?>.NOTE:xmlwf does not currentlycheck for a valid XML declaration.
- Every start tag is either empty (<tag/>)or has a corresponding end tag.
- There is exactly one root element. This element must containall other elements in the document. Only comments, whitespace, and processing instructions may come after the closeof the root element.
- All elements nest properly.
- All attribute values are enclosed in quotes (either singleor double).
If the document has a DTD, and it strictly complies with thatDTD, then the document is also considered valid.xmlwf is a non-validating parser --it does not check the DTD. However, it does supportexternal entities (see the -x option).
When an option includes an argument, you may specify the argument eitherseparately ("-d output") or concatenated with theoption ("-doutput"). xmlwfsupports both.
- If the input file is well-formed and xmlwfdoesn't encounter any errors, the input file is simply copied tothe output directory unchanged.This implies no namespaces (turns off -n) andrequires -d to specify an output file.
- -d output-dir
- Specifies a directory to contain transformedrepresentations of the input files.By default, -d outputs a canonical representation(described below).You can select different output formats using -cand -m.
The output filenames willbe exactly the same as the input filenames or "STDIN" if the input iscoming from standard input. Therefore, you must be careful that theoutput file does not go into the same directory as the inputfile. Otherwise, xmlwf will delete theinput file before it generates the output file (just like runningcat < file > file in most shells).
Two structurally equivalent XML documents have a byte-for-byteidentical canonical XML representation.Note that ignorable white space is considered significant andis treated equivalently to data.More on canonical XML can be found athttp://www.jclark.com/xml/canonxml.html .
- -e encoding
- Specifies the character encoding for the document, overridingany document encoding declaration. xmlwfsupports four built-in encodings:US-ASCII,UTF-8,UTF-16, andISO-8859-1.Also see the -w option.
- Outputs some strange sort of XML file that completelydescribes the the input file, including character postitions.Requires -d to specify an output file.
- Turns on namespace processing. (describe namespaces)-c disables namespaces.
- Tells xmlwf to process external DTDs and parameterentities.
Normally xmlwf never parses parameterentities. -p tells it to always parse them.-p implies -x.
- Normally xmlwf memory-maps the XML filebefore parsing; this can result in faster parsing on manyplatforms.-r turns off memory-mapping and uses normal fileIO calls instead.Of course, memory-mapping is automatically turned offwhen reading from standard input.
Use of memory-mapping can cause some platforms to reportsubstantially higher memory usage forxmlwf, but this appears to be a matter ofthe operating system reporting memory in a strange way; there isnot a leak in xmlwf.
- Prints an error if the document is not standalone. A document is standalone if it has no external subset and noreferences to parameter entities.
- Turns on timings. This tells Expat to parse the entire file,but not perform any processing.This gives a fairly accurate idea of the raw speed of Expat itselfwithout client overhead.-t turns off most of the output options(-d, -m, -c,...).
- Prints the version of the Expat library being used, including someinformation on the compile-time configuration of the library, andthen exits.
- Enables support for Windows code pages.Normally, xmlwf will throw an error if itruns across an encoding that it is not equipped to handle itself. With-w, xmlwf will try to use a Windows codepage. See also -e.
- Turns on parsing external entities.
Non-validating parsers are not required to resolve externalentities, or even expand entities at all.Expat always expands internal entities (?),but external entity parsing must be enabled explicitly.
External entities are simply entities that obtain theirdata from outside the XML file currently being parsed.
This is an example of an internal entity:
<!ENTITY vers '1.0.2'>
And here are some examples of external entities:
<!ENTITY header SYSTEM "header-&vers;.xml"> (parsed)<!ENTITY logo SYSTEM "logo.png" PNG> (unparsed)
- (Two hyphens.)Terminates the list of options. This is only needed if a filenamestarts with a hyphen. For example:
xmlwf -- -myfile.xml
will run xmlwf on the file-myfile.xml.
Older versions of xmlwf do not supportreading from standard input.
If an input file is not well-formed,xmlwf prints a single line describingthe problem to standard output. If a file is well formed,xmlwf outputs nothing.Note that the result code is not set.
According to the W3C standard, an XML file without adeclaration at the beginning is not considered well-formed.However, xmlwf allows this to pass.
xmlwf returns a 0 - noerr result,even if the file is not well-formed. There is no good way fora program to use xmlwf to quicklycheck a file -- it must parse xmlwf'sstandard output.
The errors should go to standard error, not standard output.
There should be a way to get -d to send itsoutput to standard output rather than forcing the user to sendit to a file.
I have no idea why anyone would want to use the-d, -c, and-m options. If someone could explain it tome, I'd like to add this information to this manpage.
Here are some XML validators on the web:
The Expat home page: http://www.libexpat.org/The W3 XML specification: http://www.w3.org/TR/REC-xml
This manual page was written by Scott Bronson <bronsonAATTrinspin.com> forthe Debian GNU/Linux system (but may be used by others). Permission isgranted to copy, distribute and/or modify this document underthe terms of the GNU Free DocumentationLicense, Version 1.1.
- WELL-FORMED DOCUMENTS
- SEE ALSO
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