I want to append a certain text at the end of a file. How can I do this?
You can append text at the end of a file using an addTextToFile action. You will have to include a section like the one below inside an action list section of your XML installer project file.
<addTextToFile>
<file>${installdir}/bin/environment.sh</file>
<text>export JAVA_HOME=${installdir}/jre
export PATH=$JAVA_HOME/bin:$PATH</text>
</addTextToFile>