XMLWF(1) XMLWF(1)
24 January 2003
NAME
xmlwf - Determines if an XML document is well-formed
SYNOPSIS
xmlwf [ -s] [ -n] [ -p] [ -x] [ -e encoding] [ -w] [ -d output-
dir] [ -c] [ -m] [ -r] [ -t] [ -v] [ file ...]
DESCRIPTION
xmlwf uses the Expat library to determine if an XML document is well-
formed. It is non-validating.
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.
WELL-FORMED DOCUMENTS
A well-formed document must adhere to the following rules:
+ The file begins with an XML declaration. For instance, <?xml
version="1.0" standalone="yes"?>. NOTE: 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 or
double).
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).
OPTIONS
When an option includes an argument, you may specify the argument
either separately ("-d output") or concatenated with the option ("-
doutput"). xmlwf supports both.
-c 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.
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-d output-dir
Specifies a directory to contain transformed representations of
the input files. By default, -d outputs a canonical
representation (described below). You can select different
output formats using -c and -m.
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
http://www.jclark.com/xml/canonxml.html .
-e encoding
Specifies the character encoding for the document, overriding any
document encoding declaration. xmlwf supports four built-in
encodings: US-ASCII, UTF-8, UTF-16, and ISO-8859-1. Also see the
-w option.
-m Outputs some strange sort of XML file that completely describes
the input file, including character positions. Requires -d to
specify an output file.
-n Turns on namespace processing. (describe namespaces) -c disables
namespaces.
-p Tells xmlwf to process external DTDs and parameter entities.
Normally xmlwf never parses parameter entities. -p tells it to
always parse them. -p implies -x.
-r Normally xmlwf memory-maps the XML file before parsing; this can
result in faster parsing on many platforms. -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.
-s 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.
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-t 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, ...).
-v Prints the version of the Expat library being used, including
some information on the compile-time configuration of the
library, and then exits.
-w 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.
-x 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)
-- (Two hyphens.) 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 -myfile.xml.
Older versions of xmlwf do not support reading from standard input.
OUTPUT
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.
BUGS
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.
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XMLWF(1) XMLWF(1)
24 January 2003
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 standard output.
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.
ALTERNATIVES
Here are some XML validators on the web:
http://www.hcrc.ed.ac.uk/~richard/xml-check.html
http://www.stg.brown.edu/service/xmlvalid/
http://www.scripting.com/frontier5/xml/code/xmlValidator.html
http://www.xml.com/pub/a/tools/ruwf/check.html
SEE ALSO
The Expat home page: http://www.libexpat.org/
The W3 XML specification: http://www.w3.org/TR/REC-xml
AUTHOR
This manual page was written by Scott Bronson <bronson@rinspin.com>
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.
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