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-
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 stdin.
A well-formed document must adhere to the following rules:
o The file begins with an XML declaration. For instance, <?xml version="1.0" stand-
alone="yes"?>. NOTE: xmlwf does not currently check for a valid XML declaration.
o Every start tag is either empty (<tag/>) or has a corresponding end tag.
o 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.
o All elements nest properly.
o 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 separate ("d out-
put") or mashed ("-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 names-
paces (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 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 STDIN. 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
Specifies the character encoding for the document, overriding any document encoding
declaration. xmlwf has 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 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. -r turns off memory-map-
ping and uses normal file IO calls instead. Of course, memory-mapping is automati-
cally turned off when reading from STDIN.
-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 output options (-d, -m -c, ...).
-v Prints the version of the Expat library being used, and then exits.
-w Enables 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)
-- For some reason, xmlwf specifically ignores "--" anywhere it appears on the command
Older versions of xmlwf do not support reading from STDIN.
If an input file is not well-formed, xmlwf outputs a single line describing the problem to
STDOUT. If a file is well formed, xmlwf outputs nothing. Note that the result code is
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 STDOUT.
The errors should go to STDERR, not stdout.
There should be a way to get -d to send its output to STDOUT 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:
22 April 2002 XMLWF(1)