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
A well-formed document must adhere to the following rules:
o The file begins with an XML declaration. For instance, . NOTE: xmlwf does not currently check
for a valid XML declaration.
o Every start tag is either empty () or has a corresponding end
o There is exactly one root element. This element must contain all
other elements in the document. Only comments, white space, and pro-
cessing instructions may come after the close of the root element.
o All elements nest properly.
o All attribute values are enclosed in quotes (either single or dou-
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 output file.
Specifies a directory to contain transformed representations of
the input files. By default, -d outputs a canonical representa-
tion (described below). You can select different output formats
using -c and -m.
The output filenames will be exactly the same as the input file-
names 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 equiva-
lently to data. More on canonical XML can be found at
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 postitions. Requires -d
to specify an output file.
-n Turns on namespace processing. (describe namespaces) -c dis-
-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 mem-
ory-mapping and uses normal file IO calls instead. Of course,
memory-mapping is automatically turned off when reading from
Use of memory-mapping can cause some platforms to report sub-
stantially 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
-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
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:
And here are some examples of external entities:
-- (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.
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
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
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 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.
24 January 2003 XMLWF(1)