xmlstarlet does not return any value for a certain element

Question

The following is happening:

The file that works as expected:

Listing what is in the xml:

# xmlstarlet el -a table.xml
table
table/rec
table/rec/@id
table/rec/numField
table/rec/stringField
table/rec
table/rec/@id
table/rec/numField
table/rec/stringField
table/rec
table/rec/@id
table/rec/numField
table/rec/stringField

Selecting a specific element:

# xmlstarlet sel -t -v "//table/rec/numField" table.xml
123
346
-23

Raw data:

#cat table.xml
<?xml version="1.0" encoding="UTF-8"?>
<table>
  <rec id="1">
    <numField>123</numField>
    <stringField>String Value</stringField>
  </rec>
  <rec id="2">
    <numField>346</numField>
    <stringField>Text Value</stringField>
  </rec>
    <rec id="3">
    <numField>-23</numField>
    <stringField>stringValue</stringField>
  </rec>
</table>

Next run with test.xml

# xmlstarlet el -a test.xml

filelists
filelists/@xmlns
filelists/@packages
filelists/package
filelists/package/@pkgid
filelists/package/@name
filelists/package/@arch
filelists/package/version
filelists/package/version/@epoch
filelists/package/version/@ver
filelists/package/version/@rel
filelists/package/file
filelists/package/file
filelists/package/file
filelists/package/file
filelists/package/file/@type

Querying the same way as the previous one:

# xmlstarlet sel -t -v "//filelists/package/file" test.xml
#

The content of the file:

#cat test.xml
<?xml version="1.0" encoding="UTF-8"?>
  <filelists xmlns="http://linux.duke.edu/metadata/filelists" packages="8">
    <package pkgid="fc2a76ba4e6e0b2bc704b9e7bcb205ca1c11e93b" name="bigtop-utils" arch="noarch">
      <version epoch="0" ver="0.4+300" rel="1.cdh4.0.1.p0.1.el6"/>
      <file>/etc/default/bigtop-utils</file>
      <file>/usr/libexec/bigtop-detect-javahome</file>
      <file>/usr/share/doc/bigtop-utils-0.4+300/LICENSE</file>
      <file type="dir">/usr/share/doc/bigtop-utils-0.4+300</file>
    </package>
  </filelists>

I guess I don't get something here.

Why cant I display the content of those file tags? Do I need to escape it somehow?

Answer 1

You have to declare the namespace using the -N switch and use it for all elements inside its scope (note that I've split the command in lines to avoid markdown scrolling):

xmlstarlet sel \
    -N 'x=http://linux.duke.edu/metadata/filelists' \
    -t \
    -v \
    "//x:filelists/x:package/x:file" \
test.xml

It yields:

/etc/default/bigtop-utils
/usr/libexec/bigtop-detect-javahome
/usr/share/doc/bigtop-utils-0.4+300/LICENSE
/usr/share/doc/bigtop-utils-0.4+300

Answer 2

Starting with version 1.2.1 you can use de default namespace _
(drop the -N argument)

xmlstarlet sel -t -v "//_:filelists/_:package/_:file" test.xml

As explained here:

1.3. A More Convenient Solution

XML documents can also use different namespace prefixes, on any element in the document. In order to handle namespaces with greater ease, XMLStarlet (versions 1.2.1+) will use the namespace prefixes declared on the root element of the input document. The default namespace will be bound to the prefixes "_" and "DEFAULT" (in versions 1.5.0+).