Support property settings for Linux.

build.xml

@@ -18,14 +18,17 @@
         we're executing on.  We use this to decide which properties files
         to load.
 
-        Values: windows, macosx, other.
+        Values: windows, macosx, linux, other.
     -->
     <condition property="os.family" value="windows">
         <os family="windows"/>
     </condition>
     <condition property="os.family" value="macosx">
         <os family="mac"/>
     </condition>
+    <condition property="os.family" value="linux">
+        <os family="unix" name="Linux"/>
+    </condition>
     <property name="os.family" value="other"/>
 
     <!--
@@ -1281,4 +1284,4 @@
         </echoproperties>
     </target>
 
-</project>
+</project>

linux.properties

@@ -0,0 +1,7 @@
+#
+# linux.properties
+#
+# Properties for Linux builds.  Properties defined here override
+# those defined in default.properties, but may be overridden by
+# properties defined in a machine-specific build.properties file.
+#