The mvn
command is actually a batch command, so you can't execute it directly. Try this:
<exec executable="cmd.exe">
<arg value="/c"/>
<arg value="mvn.bat"/>
<arg value="install:install-file"/>
<arg value="-Dfile=c:\dev\common\somejar.jar"/>
<arg value ="-DgroupId=com.myco.gt"/>
<arg value="-DartifactId=somejar"/>
<arg value="-Dversion=1.2.0"/>
<arg value="-Dpackaging=jar"/>
<arg value="-DgeneratePOM=true"/>
</exec>