Update AppSetting. Note an AppSetting with the correct key must be defined in the configuration file. <project name="Update AppSettings"> <target name="update-config-file"> <tempfile property="temp.config.file" /> <copy file="${config.file}" tofile="${temp.config.file}"/> <xslt in="${temp.config.file}" out="${config.file}"> <style> <string><![CDATA[<?xml version="1.0"?> <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform"> <xsl:template match="@*|node()"> <xsl:copy> <xsl:apply-templates select="@*|node()"/> </xsl:copy> </xsl:template> <xsl:template match="/configuration/appSettings/add[@key='${appsetting.key}']/@value"> <xsl:attribute name='value'>${appsetting.value}</xsl:attribute> </xsl:template> </xsl:stylesheet>]]></string> </style> </xslt> </target> </project>