--- a/nbbuild/antsrc/org/netbeans/nbbuild/AutoUpdate.java	Tue Mar 08 07:32:11 2011 +0100
+++ a/nbbuild/antsrc/org/netbeans/nbbuild/AutoUpdate.java	Tue Mar 08 09:31:55 2011 +0100
@@ -88,6 +88,7 @@ 
 public class AutoUpdate extends Task {
     private List<Modules> modules = new ArrayList<Modules>();
     private FileSet nbmSet;
+    private File download;
     private File dir;
     private File cluster;
     private URL catalog;
@@ -112,6 +113,10 @@ 
     public void setToDir(File dir) {
         this.cluster = dir;
     }
+    
+    public void setDownloadDir(File dir) {
+        this.download = dir;
+    }
 
     /** Forces rewrite even the version of a module is not newer */
     public void setForce(boolean force) {
@@ -126,8 +131,14 @@ 
 
     @Override
     public void execute() throws BuildException {
+        boolean downloadOnly = false;
         if ((dir != null) == (cluster != null)) {
-            throw new BuildException("Specify either todir or installdir");
+            if (dir == null && cluster == null && download != null) {
+                log("Going to download NBMs only to " + download);
+                downloadOnly = true;
+            } else {
+                throw new BuildException("Specify either todir or installdir");
+            }
         }
         Map<String, ModuleItem> units;
         if (catalog != null) {
@@ -194,7 +205,7 @@ 
             boolean delete = false;
             File lastM = null;
             try {
-                if (uu.getURL().getProtocol().equals("file")) {
+                if (download == null && uu.getURL().getProtocol().equals("file")) {
                     try {
                         tmp = new File(uu.getURL().toURI());
                     } catch (URISyntaxException ex) {
@@ -206,9 +217,13 @@ 
                 }
                 final String dash = uu.getCodeName().replace('.', '-');
                 if (tmp == null) {
-                    tmp = File.createTempFile(dash, ".nbm");
-                    tmp.deleteOnExit();
-                    delete = true;
+                    if (download != null) {
+                        tmp = new File(download, dash + ".nbm");
+                    } else {
+                        tmp = File.createTempFile(dash, ".nbm");
+                        tmp.deleteOnExit();
+                        delete = true;
+                    }
                     Get get = new Get();
                     get.setProject(getProject());
                     get.setTaskName("get:" + uu.getCodeName());
@@ -217,6 +232,9 @@ 
                     get.setVerbose(true);
                     get.execute();
                 }
+                if (downloadOnly) {
+                    continue;
+                }
 
                 File whereTo = dir != null ? new File(dir, uu.targetcluster) : cluster;
                 whereTo.mkdirs();
--- a/nbbuild/test/unit/src/org/netbeans/nbbuild/AutoUpdateTest.java	Tue Mar 08 07:32:11 2011 +0100
+++ a/nbbuild/test/unit/src/org/netbeans/nbbuild/AutoUpdateTest.java	Tue Mar 08 09:31:55 2011 +0100
@@ -67,6 +67,27 @@ 
         super(name);
     }
 
+    public void testJustDownloadNBMs() throws Exception {
+        File nbm = generateNBM("org-netbeans-api-annotations-common.nbm",
+            "netbeans/config/Modules/org-netbeans-api-annotations-common.xml",
+            "netbeans/modules/org-netbeans-api-annotations-common.jar");
+        assertTrue("NBM file created", nbm.isFile());
+
+        File target = new File(getWorkDir(), "target");
+        target.mkdirs();
+
+        execute(
+            "autoupdate.xml", "-verbose", "-Ddir=" + nbm.getParent(),
+            "-Dincludes=org.netbeans.api.annotations.common",
+            "-Dtarget=" + target,
+            "mirror"
+        );
+        
+        File[] arr = target.listFiles();
+        assertEquals("One item in the array:\n" + getStdOut(), 1, arr.length);
+        assertEquals("It is the NBM file", nbm.getName(), arr[0].getName());
+        assertEquals("Length is the same", nbm.length(), arr[0].length());
+    }
     public void testDirectlySpecifiedNBMs() throws Exception {
         File nbm = generateNBM("org-netbeans-api-annotations-common.nbm",
             "netbeans/config/Modules/org-netbeans-api-annotations-common.xml",
--- a/nbbuild/test/unit/src/org/netbeans/nbbuild/autoupdate.xml	Tue Mar 08 07:32:11 2011 +0100
+++ a/nbbuild/test/unit/src/org/netbeans/nbbuild/autoupdate.xml	Tue Mar 08 09:31:55 2011 +0100
@@ -59,4 +59,17 @@ 
         </autoupdate>
 
     </target>
+    
+    <target name="mirror">
+        <echo message="${root}"/>
+
+        <taskdef classname="org.netbeans.nbbuild.AutoUpdate" name="autoupdate" classpath="${nb_all}/nbbuild/nbantext.jar"/>
+
+        <autoupdate downloaddir="${target}">
+            <nbms dir="${dir}">
+                <include name="*.nbm"/>
+            </nbms>
+            <modules includes="${includes}"/>
+        </autoupdate>
+    </target>
 </project>