How to extract the GAV from a pom.xml file in a shell script

Question

I need to extract the Maven GAV (groupId, artifactId, version) from a large number of pom.xml files. Not all of the POMs have a parent POM declaration, so the inheritance between parent GAV and project GAV needs to be taken into account.

I'd only like to use tools that can be easily scripted in a linux shell, eg bash.

Answer 1

The best solution I could find is using an XSL transformation. Create a file extract-gav.xsl with the following content:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0"
    xmlns:pom="http://maven.apache.org/POM/4.0.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

    <xsl:output indent="yes" omit-xml-declaration="yes"/>
    <xsl:strip-space elements="*"/>

    <xsl:template match="/pom:project">
        <!-- this XML element just serves as a bracket and may be omitted -->
        <xsl:element name="artifact">
            <xsl:text>&#10;</xsl:text>

            <!-- process coordinates declared at project and project/parent -->
            <xsl:apply-templates select="pom:groupId|pom:parent/pom:groupId" mode="copy-coordinate"/>
            <xsl:apply-templates select="pom:artifactId|pom:parent/pom:artifactId" mode="copy-coordinate"/>
            <xsl:apply-templates select="pom:version|pom:parent/pom:version" mode="copy-coordinate"/>
        </xsl:element>
    </xsl:template>

    <xsl:template match="*" mode="copy-coordinate">
        <!-- omit parent coordinate if same coordinate is explicitly specified on project level -->
        <xsl:if test="not(../../*[name(.)=name(current())])">

            <!-- write coordinate as XML element without namespace declarations -->
            <xsl:element name="{local-name()}">
               <xsl:value-of select="."/>
            </xsl:element>
            <xsl:text>&#10;</xsl:text>
        </xsl:if>
    </xsl:template>

</xsl:stylesheet>

This transformation can then be invoked in a shell (assuming that you have the libxslt installed) with th command xsltproc extract-gav.xsl pom.xml

This produces the output in the following format:

<artifact>
  <groupId>org.example.group</groupId>
  <artifactId>example-artifact</artifactId>
  <version>1.2.0</version>
</artifact>

If you need a different format, the XSL transformation should be easy enough to adapt so that it suits your needs. Eg the following transformation writes the GAV as tab-separated plain text:

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0"
    xmlns:pom="http://maven.apache.org/POM/4.0.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

    <xsl:output method="text"/>
    <xsl:strip-space elements="*"/>

    <xsl:template match="/pom:project">
        <!-- process coordinates declared at project and project/parent -->
        <xsl:apply-templates select="pom:groupId|pom:parent/pom:groupId" mode="copy-coordinate"/>
        <xsl:apply-templates select="pom:artifactId|pom:parent/pom:artifactId" mode="copy-coordinate"/>
        <xsl:apply-templates select="pom:version|pom:parent/pom:version" mode="copy-coordinate"/>
        <xsl:text>&#10;</xsl:text>
    </xsl:template>

    <xsl:template match="*" mode="copy-coordinate">
        <xsl:if test="not(../../*[name(.)=name(current())])">
            <xsl:value-of select="."/>
            <xsl:text>&#9;</xsl:text>
        </xsl:if>
    </xsl:template>

</xsl:stylesheet>

Answer 2

grep -v '\[' <( mvn help:evaluate -Dexpression="project.groupId" 2>/dev/null && 
    mvn help:evaluate -Dexpression="project.artifactId" 2>/dev/null && 
    mvn help:evaluate -Dexpression="project.version" 2>/dev/null )

Answer 3

I use a groovy script called pom that I placed on PATH. It looks like this:

#!/usr/bin/env groovy

def cli = new CliBuilder(usage:'pom')
cli.h('print usage')
cli.n('do not auto-print output')
cli.p(args:1, argName:'pom', 'the POM file to use')

def options = cli.parse(args)
def arguments = options.arguments()

if (options.h || arguments.size() == 0 ) {
    println cli.usage()
} else {
    def fileName = options.p ? options.p : "pom.xml"
    def script = arguments[0]

    def output = Eval.x(new XmlSlurper().parse(new File(fileName)), "x.${script}")
    if (!options.n) println output
}

Now you can extract values like this:

pom version
pom groupId
pom 'properties."project.build.sourceEncoding"'
pom -n 'modules.module.each { println it }'
pom -n 'dependencyManagement.dependencies.dependency.each { \
    println "${it.groupId}:${it.artifactId}:${it.version}" \
}'