ant note

  <target name="test" description="Record build information">
<!-- The name of the file that holds the build information. If no such file exists, a new
   one gets created. -->
<propertyfile file="./build.info">
<!-- Initial build number is 0001. Then, any subsequent build increments

this number by one  each time. -->
<entry default="0001" key="build.number" operation="+" pattern="0000" type="int" />
<!-- Records the current time to the same file. -->
<entry default="now" key="build.time" pattern="yyyy.MM.dd-HH.mm" type="date" />
</propertyfile>
<replace
    file="./a.txt"
    value="defaultvalue"
    propertyFile="./build.info">
<replacefilter
    token="build.number" property="build.number"/>
</replace>
<loadproperties srcFile="./build.info"/>
<echo message="${build.number}"/> 
</target>