Scripting: what is the easiest to extract a value in a tag of a XML file?

Question

I want to read a pom.xml ('Project Object Model' of Maven) and extract the version information. Here is an example:

<?xml version="1.0" encoding="UTF-8"?><project 
xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">

    <modelVersion>4.0.0</modelVersion>
    <groupId>com.mycompany</groupId>
    <artifactId>project-parent</artifactId>
    <name>project-parent</name>
    <version>1.0.74-SNAPSHOT</version>
    <dependencies>
        <dependency>
        <groupId>com.sybase.jconnect</groupId>
        <artifactId>jconnect</artifactId>
        <version>6.05-26023</version>
    </dependency>
    <dependency>
        <groupId>joda-time</groupId>
        <artifactId>joda-time</artifactId>
        <version>1.5.2</version>
    </dependency>
    <dependency>
        <groupId>com.sun.jdmk</groupId>
        <artifactId>jmxtools</artifactId>
        <version>1.2.1</version>
    </dependency>
    <dependency>
        <groupId>org.easymock</groupId>
        <artifactId>easymock</artifactId>
        <version>2.4</version>
    </dependency>       
</dependencies>
</project>

How can I extract the version '1.0.74-SNAPSHOT' from above?

Would love to be able to do so using simple bash scripting sed or awk. Otherwise a simple python is preferred.

EDIT

1. Constraint

   The linux box is in a corporate environment so I can only use tools that are already installed (not that I cannot request utility such as xml2, but I have to go through a lot of red-tape). Some of the solutions are very good (learn a few new tricks already), but they may not be applicable due to the restricted environment

2. updated xml listing

   I added the dependencies tag to the original listing. This will show some hacky solution may not work in this case

3. Distro

   The distro I am using is RHEL4

Answer 1

xml2 can convert xml to/from line-oriented format:

xml2 < pom.xml  | grep /project/version= | sed 's/.*=//'

Answer 2

Other way: xmlgrep and XPath:

xmlgrep --text_only '/project/version' pom.xml

Disadvantage: slow

Answer 3

Using python

$ python -c 'from xml.etree.ElementTree import ElementTree; print ElementTree(file="pom.xml").findtext("{http://maven.apache.org/POM/4.0.0}version")'
1.0.74-SNAPSHOT

Using xmlstarlet

$ xml sel -N x="http://maven.apache.org/POM/4.0.0" -t -m 'x:project/x:version' -v . pom.xml
1.0.74-SNAPSHOT

Using xmllint

$ echo -e 'setns x=http://maven.apache.org/POM/4.0.0\ncat /x:project/x:version/text()' | xmllint --shell pom.xml | grep -v /
1.0.74-SNAPSHOT

Answer 4

Clojure way. Requires only jvm with special jar file:

java -cp clojure.jar clojure.main -e "(use 'clojure.xml) (->> (java.io.File. \"pom.xml\") (clojure.xml/parse) (:content) (filter #(= (:tag %) :version)) (first) (:content) (first) (println))"

Scala way:

java -Xbootclasspath/a:scala-library.jar -cp scala-compiler.jar scala.tools.nsc.MainGenericRunner -e 'import scala.xml._; println((XML.load(new java.io.FileInputStream("pom.xml")) match { case <project>{children @ _*}</project> => for (i <- children if (i  match { case <version>{children @ _*}</version> => true; case _ => false;  }))  yield i })(0) match { case <version>{Text(x)}</version> => x })'

Groovy way:

java -classpath groovy-all.jar groovy.ui.GroovyMain -e 'println (new XmlParser().parse(new File("pom.xml")).value().findAll({ it.name().getLocalPart()=="version" }).first().value().first())'

Answer 5

Here's an alternative in Perl

$ perl -MXML::Simple -e'print XMLin("pom.xml")->{version}."\n"'
1.0.74-SNAPSHOT

It works with the revised/extended example in the questions which has multiple "version" elements at different depths.

Answer 6

Hacky way:

perl -e '$_ = join "", <>; m!<project[^>]*>.*\n(?:    |\t)<version[^>]*>\s*([^<]+?)\s*</version>.*</project>!s and print "$1\n"' pom.xml

Relies on correct indentation of the required <version>

Answer 7

Work out a very clumsy, one-liner solution

python -c "from xml.dom.minidom import parse;dom = parse('pom.xml');print [n for n in dom.getElementsByTagName('version') if n.parentNode == dom.childNodes[0]][0].toxml()" | sed -e "s/.*>\(.*\)<.*/\1/g"

The sed at the end is very ugly but i was not able to print out the text of the node with mindom alone.

Update from _Vi:

Less hacky Python version:

python -c "from xml.dom.minidom import parse;dom = parse('pom.xml');print [i.childNodes.item(0).nodeValue for i in dom.firstChild.childNodes if i.nodeName == 'version'].pop()"

Update from me

Another version:

    python -c "from  xml.dom.minidom import parse;dom = parse('pom.xml');print [n.firstChild.data for n in dom.childNodes[0].childNodes if n.firstChild and n.tagName == 'version']"

Answer 8

XSLT way:

<?xml version="1.0" encoding="ISO-8859-1"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
        <xsl:output method="text"/>

        <xsl:template match="/">
                <xsl:for-each select="*[local-name()='project']">
                    <xsl:for-each select="*[local-name()='version']">
                        <xsl:value-of select="text()"/>
                    </xsl:for-each>
                </xsl:for-each>
        </xsl:template>
</xsl:stylesheet>

xalan -xsl x.xsl -in pom.xml

Answer 9

if "There are a lot of version tag in the xml" then you better forget about doing it with "simple tools" and regexps, that won't do.

try this python (no dependencies):

from xml.dom.minidom import parse

dom = parse('pom.xml')
project = dom.getElementsByTagName('project')[0]
for node in project.childNodes:
    if node.nodeType == node.ELEMENT_NODE and node.tagName == 'version':
        print node.firstChild.nodeValue

Answer 10

awk works fine without using any extra tools.
cat pod.xml

<project>
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.networks.app</groupId>
  <artifactId>operation-platform</artifactId>
  <version>1.0.0</version>
  <packaging>tar.xz</packaging>
  <description>POM was created by Sonatype Nexus</description>
</project>

simple and legible way to get the value of <packaging> tag:

cat pod.xml | awk -F'[<>]' '/packaging/{print $3}'

Answer 11

Here is a one-liner using sed:

sed '/<dependencies>/,/<\/dependencies>/d;/<version>/!d;s/ *<\/\?version> *//g' pom.xml

Answer 12

Return_text_val=$(xmllint --xpath "//*[local-name()='$TagElmnt']" $FILE )

Here, try this:

$TagElmnt - TagName
$FILE - xml file to parse

Answer 13

I know your question says Linux but if you have the need to do this on Windows without the need of any 3rd party tools such that you can put it in a batch file, Powershell can extract any node from the your pom.xml file like so:

powershell -Command "& {select-xml //pom:project/pom:properties/pom:mypluginversion -path pom.xml -Namespace  @{pom='http://maven.apache.org/POM/4.0.0'} | foreach {$_.Node.Innerxml}}" > myPluginVersion.txt

Answer 14

sed -n "/<name>project-parent/{n;s/.*>\(.*\)<.*/\1/p;q}" pom.xml

The -n option avoids printing non-matching lines; first match (/.../) is on the line before the one with wanted text; the n command skips to next line, where s extracts relevant info thru a capturing group (\(...\)), and a backreference (\1). p prints out, q quits.