XMLWF(1) UNIX Programmer's Manual XMLWF(1)
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 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 con-
tain 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).
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
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output file.
-d output-dir
Specifies a directory to contain transformed represen-
tations 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 the input file, including character pos-
titions. 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
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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.
-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 out-
put options (-d, -m, -c, ...).
-v Prints the version of the Expat library being used,
including some information on the compile-time confi-
guration 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 exter-
nal 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.
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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 stan-
dard output.
The errors should go to standard error, not standard output.
There should be a way to get -d to send its output to stan-
dard 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:
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
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
<bronson@rinspin.com> for the Debian GNU/Linux system (but
may be used by others). Permission is granted to copy, dis-
tribute and/or modify this document under the same terms as
Expat itself.
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