build.gradle

//task to update file content
task updateBuildNum {
   def productVersion="1.2.3.0"
   def buildNum="1.2.3.4521"
   String contents = new File( '/tmp/dir/BuildNum.plist' ).getText( 'UTF-8' )
   contents = contents.replaceAll( 'version = "0.0.0.0"', 'version = '+'"'+"${productVersion}"+'"')
   contents = contents.replaceAll( 'buildNum = "0.0.0.0"', 'buildNum = '+'"'+"${buildNum}"+'"')
   new File( 'build/BuildNum.plist' ).write( contents, 'UTF-8' )
}