Using ant to detect os and set property

Question

I want to set a property in an ant task differently by os type.

The property is a directory, in windows i want it to be "c:\flag" in unix/linux "/opt/flag".

My current script only works when i run it with the default target, but why ?

    <target name="checksw_path" depends="if_windows, if_unix"/>

<target name="checkos">
 <condition property="isWindows">
  <os family="windows" />
 </condition>

 <condition property="isLinux">
  <os family="unix" />
 </condition>
</target>

<target name="if_windows" depends="checkos" if="isWindows">
   <property name="sw.root" value="c:\flag" />
 <echo message="${sw.root}"/>
</target>

<target name="if_unix" depends="checkos" if="isLinux">
 <property name="sw.root" value="/opt/flag" />
 <echo message="${sw.root}"/>
</target>

In all my ant targets i've added a "depends=checksw_path".

If i run the default target in windows i've got correctly "c:\flag" but if i run a non default target i've got that the debug goes in the if_windows but the instruction " " does not set the property that remains /opt/flag. I'm using ant 1.7.1.

Answer 1

Move your condition out of the <target />, as your target probably isn't invoked.

 <condition property="isWindows">
                    <os family="windows" />
 </condition>

 <condition property="isLinux">
                    <os family="unix" />
 </condition>

Answer 2

Did you try this slightly different method? http://blog.loxal.net/2008/09/how-to-check-os-with-ant-using-if.html

Answer 3

I solved executing the ant task with the value for sw.root using -Dsw.root=c:\flag (for windows) or -Dsw.root=/opt/superwaba (for linux).

Anyway thanks

Answer 4

Try setting <sysproperty key="foobar" value="fowl"/> in your java task. Then, in your app, use System.getProperty("foobar");

Answer 5

You need to set value "true" to the property for the if condition to work. See the code below:

<target name="checkos">
    <condition property="isWindows" value="true">
            <os family="windows" />
    </condition>

    <condition property="isLinux" value="true">
            <os family="unix" />
    </condition>
</target>

HTH, Hari