Updated: 24 January 2003Index
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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 to
determine if an XML document is well-formed. It is
If you do not specify any files on the command-line, and you
have a recent version of xmlwf, the
input file will be read from standard input.
A well-formed document must adhere to the
The file begins with an XML declaration. For instance,
<?xml version="1.0" standalone="yes"?>.
xmlwf does not currently
check 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 contain
all other elements in the document. Only comments, white
space, and processing instructions may come after the close
of the root element.
All elements nest properly.
All attribute values are enclosed in quotes (either single
If the document has a DTD, and it strictly complies with that
DTD, then the document is also considered valid.
xmlwf is a non-validating parser —
it does not check the DTD. However, it does support
external entities (see the -x option).
When an option includes an argument, you may specify the argument either
separately ("-d output") or concatenated with the
option ("-doutput"). xmlwf
If the input file is well-formed and xmlwf
doesn’t encounter any errors, the input file is simply copied to
the output directory unchanged.
This implies no namespaces (turns off -n) and
requires -d to specify an output file.
- -d output-dir
Specifies a directory to contain transformed
representations of the input files.
By default, -d outputs a canonical representation
You can select different output formats using -c
The output filenames will
be exactly the same as the input filenames or "STDIN" if the input is
coming from standard input. Therefore, you must be careful that the
output file does not go into the same directory as the input
file. Otherwise, xmlwf will delete the
input file before it generates the output file (just like running
cat < file > file in most shells).
Two structurally equivalent XML documents have a byte-for-byte
identical canonical XML representation.
Note that ignorable white space is considered significant and
is treated equivalently to data.
More on canonical XML can be found at
- -e encoding
Specifies the character encoding for the document, overriding
any document encoding declaration. xmlwf
supports four built-in encodings:
Also see the -w option.
Outputs some strange sort of XML file that completely
describes the input file, including character positions.
Requires -d to specify an output file.
Turns on namespace processing. (describe namespaces)
-c disables namespaces.
Tells xmlwf to process external DTDs and parameter
Normally xmlwf never parses parameter
entities. -p tells it to always parse them.
-p implies -x.
Normally xmlwf memory-maps the XML file
before parsing; this can result in faster parsing on many
-r turns off memory-mapping and uses normal file
IO calls instead.
Of course, memory-mapping is automatically turned off
when reading from standard input.
Use of memory-mapping can cause some platforms to report
substantially higher memory usage for
xmlwf, but this appears to be a matter of
the operating system reporting memory in a strange way; there is
not a leak in xmlwf.
Prints an error if the document is not standalone.
A document is standalone if it has no external subset and no
references 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 itself
without client overhead.
-t turns off most of the output options
(-d, -m, -c,
Prints the version of the Expat library being used, including some
information on the compile-time configuration of the library, and
Enables support for Windows code pages.
Normally, xmlwf will throw an error if it
runs across an encoding that it is not equipped to handle itself. With
-w, xmlwf will try to use a Windows code
page. See also -e.
Turns on parsing external entities.
Non-validating parsers are not required to resolve external
entities, 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 their
data 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)
Terminates the list of options. This is only needed if a filename
starts with a hyphen. For example:
xmlwf — -myfile.xml
will run xmlwf on the file
Older versions of xmlwf do not support
reading from standard input.
If an input file is not well-formed,
xmlwf prints a single line describing
the 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 a
declaration 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 for
a program to use xmlwf to quickly
check a file — it must parse xmlwf‘s
The errors should go to standard error, not standard output.
There should be a way to get -d to send its
output to standard output rather than forcing the user to send
it to a file.
I have no idea why anyone would want to use the
-d, -c, and
-m options. If someone could explain it to
me, 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 <[email protected]> for
the Debian GNU/Linux system (but may be used by others). Permission is
granted to copy, distribute and/or modify this document under
the terms of the GNU Free Documentation
License, Version 1.1.
- WELL-FORMED DOCUMENTS
- SEE ALSO