Question

Here is a property file:

test.url=https:\\url:port
test.path=/home/folder
test.location=Location
test.version=1

And the following ant task:

I can pass temporary value for one run of a task:

ant -Dtest.path=new_path test_props

How can I overwrite test.path value with one I pass using -D key? In order, after the same launch, the value of test.path would change to one I pass above?

The following variants don’t work:

<entry key="test.path" value="${test.path}"/>

or

<propertycopy name="test.path" from="${test_path}"/>

Answer 1

If you want to permanently change a file, you could use the task.

I’d do the following:

Create a sample property file, like default.properties.sample.

Create a target that receives the given -D property, then, if it’s been informed, does a replace on file default.properties.sample saving it into a default.properties file. The default.properties.sample would have these lines:

test.url=https:\\url:port
test.path=@test_path@
test.location=Location
test.version=1

The action would replace the @test_path@ token with the real value of the property, as informed in the -D parameter, then save the resulting file as default.properties. Something like:

<copy file="default.properties.sample" toFile="default.properties" />
<replace file="default.properties" token="@test_path@" value="${test.path}" />

Some adjustments need to be made, like: only replace the property if the -D parameter is informed, or else the file would be replaced every time.

Paths and like should also be adjusted to your needs.

---

I’ve tested the following scenario and it worked for me:

I’ve created two files: a build.xml and a default.properties.sample. Their contents is as follows:

build.xml

<?xml version="1.0" encoding="UTF-8"?>
<project name="BuildTest" default="showProperties" basedir=".">
    <property file="default.properties"/>

    <target name="showProperties">
        <echo message="test.property=${test.property}"/>
    </target>

    <target name="replace">
        <fail unless="new.test.property" message="Property new.test.property should be informed via -D parameter"/>
        <copy file="default.properties.sample" toFile="default.properties"/>
        <replace file="default.properties" token="@test_property@" value="${new.test.property}"/>
    </target>
</project>

default.properties.sample:

test.property=@test_property@

And they run to the following tests:

Default run:

C:\Filipe\Projects\BuildTest>ant
Buildfile: C:\Filipe\Projects\BuildTest\build.xml

showProperties:
     [echo] test.property=${test.property}

BUILD SUCCESSFUL
Total time: 0 seconds

Error control:

C:\Filipe\Projects\BuildTest>ant replace
Buildfile: C:\Filipe\Projects\BuildTest\build.xml

replace:

BUILD FAILED
C:\Filipe\Projects\BuildTest\build.xml:10: Property new.test.property should be      informed via -D parameter
Total time: 0 seconds

Replace of property:

C:\Filipe\Projects\BuildTest>ant replace -Dnew.test.property="This is a New Value"
Buildfile: C:\Filipe\Projects\BuildTest\build.xml

replace:
     [copy] Copying 1 file to C:\Filipe\Projects\BuildTest

BUILD SUCCESSFUL
Total time: 0 seconds

Property file after replacement:

C:\Filipe\Projects\BuildTest>type default.properties
test.property=This is a New Value

And in a subsequent runs the new value of the test.property is present:

C:\Filipe\Projects\BuildTest>ant
Buildfile: C:\Filipe\Projects\BuildTest\build.xml

showProperties:
     [echo] test.property=This is a New Value

BUILD SUCCESSFUL
Total time: 0 seconds

I think that is what you’re looking for.