Added commands to list paths.

Added protection against bad input on some command-lines.

@@ -31,4 +31,14 @@ public abstract class AbstractShellCommand extends OsgiCommandSupport {
         System.out.println(String.format(format, args));
     }
 
+    /**
+     * Prints the arguments using the specified format to error stream.
+     *
+     * @param format format string; see {@link String#format}
+     * @param args   arguments
+     */
+    public static void error(String format, Object... args) {
+        System.err.println(String.format(format, args));
+    }
+
 }

@@ -35,11 +35,16 @@ public class ClusterDevicesCommand extends ClustersListCommand {
         int cid = Integer.parseInt(id);
         init();
         TopologyCluster cluster = service.getCluster(topology, clusterId(cid));
-        List<DeviceId> ids = Lists.newArrayList(service.getClusterDevices(topology, cluster));
-        Collections.sort(ids, ID_COMPARATOR);
-        for (DeviceId deviceId : ids) {
-            print("%s", deviceId);
+        if (cluster == null) {
+            error("No such cluster %s", cid);
+        } else {
+            List<DeviceId> ids = Lists.newArrayList(service.getClusterDevices(topology, cluster));
+            Collections.sort(ids, ID_COMPARATOR);
+            for (DeviceId deviceId : ids) {
+                print("%s", deviceId);
+            }
         }
+
         return null;
     }
 

@@ -24,8 +24,12 @@ public class ClusterLinksCommand extends ClustersListCommand {
         int cid = Integer.parseInt(id);
         init();
         TopologyCluster cluster = service.getCluster(topology, clusterId(cid));
-        for (Link link : service.getClusterLinks(topology, cluster)) {
-            print(linkString(link));
+        if (cluster == null) {
+            error("No such cluster %s", cid);
+        } else {
+            for (Link link : service.getClusterLinks(topology, cluster)) {
+                print(linkString(link));
+            }
         }
         return null;
     }

@@ -42,7 +42,12 @@ public class DevicePortsListCommand extends DevicesListCommand {
                 printDevice(service, device);
             }
         } else {
-            printDevice(service, service.getDevice(deviceId(uri)));
+            Device device = service.getDevice(deviceId(uri));
+            if (device == null) {
+                error("No such device %s", uri);
+            } else {
+                printDevice(service, device);
+            }
         }
         return null;
     }

@@ -56,10 +56,12 @@ public class DevicesListCommand extends AbstractShellCommand {
      * @param device  infrastructure device
      */
     protected void printDevice(DeviceService service, Device device) {
-        print(FMT, device.id(), service.isAvailable(device.id()),
-              service.getRole(device.id()), device.type(),
-              device.manufacturer(), device.hwVersion(), device.swVersion(),
-              device.serialNumber());
+        if (device != null) {
+            print(FMT, device.id(), service.isAvailable(device.id()),
+                  service.getRole(device.id()), device.type(),
+                  device.manufacturer(), device.hwVersion(), device.swVersion(),
+                  device.serialNumber());
+        }
     }
 
 }

@@ -16,6 +16,7 @@ import static org.onlab.onos.net.DeviceId.deviceId;
 public class LinksListCommand extends AbstractShellCommand {
 
     private static final String FMT = "src=%s/%s, dst=%s/%s, type=%s";
+    private static final String COMPACT = "%s/%s-%s/%s";
 
     @Argument(index = 0, name = "uri", description = "Device ID",
               required = false, multiValued = false)
@@ -43,4 +44,16 @@ public class LinksListCommand extends AbstractShellCommand {
                              link.dst().deviceId(), link.dst().port(), link.type());
 
     }
+
+    /**
+     * Returns a compact string representing the given link.
+     *
+     * @param link infrastructure link
+     * @return formatted link string
+     */
+    public static String compactLinkString(Link link) {
+        return String.format(COMPACT, link.src().deviceId(), link.src().port(),
+                             link.dst().deviceId(), link.dst().port());
+    }
+
 }

@@ -2,10 +2,12 @@ package org.onlab.onos.cli.net;
 
 import org.apache.karaf.shell.commands.Argument;
 import org.apache.karaf.shell.commands.Command;
+import org.onlab.onos.net.Link;
 import org.onlab.onos.net.Path;
 
 import java.util.Set;
 
+import static org.onlab.onos.cli.net.LinksListCommand.compactLinkString;
 import static org.onlab.onos.net.DeviceId.deviceId;
 
 /**
@@ -16,13 +18,13 @@ import static org.onlab.onos.net.DeviceId.deviceId;
          description = "Lists all shortest-paths paths between the specified source and destination devices")
 public class PathListCommand extends TopologyCommand {
 
-    private static final String FMT = "src=%s/%s, dst=%s/%s, type=%s";
+    private static final String SEP = "==>";
 
     @Argument(index = 0, name = "src", description = "Source device ID",
               required = true, multiValued = false)
     String src = null;
 
-    @Argument(index = 0, name = "dst", description = "Destination device ID",
+    @Argument(index = 1, name = "dst", description = "Destination device ID",
               required = true, multiValued = false)
     String dst = null;
 
@@ -36,8 +38,20 @@ public class PathListCommand extends TopologyCommand {
         return null;
     }
 
-    private String pathString(Path path) {
-        return path.toString();
+    /**
+     * Produces a formatted string representing the specified path.
+     *
+     * @param path network path
+     * @return formatted path string
+     */
+    protected String pathString(Path path) {
+        StringBuilder sb = new StringBuilder();
+        for (Link link : path.links()) {
+            sb.append(compactLinkString(link)).append(SEP);
+        }
+        sb.delete(sb.lastIndexOf(SEP), sb.length());
+        sb.append("; cost=").append(path.cost());
+        return sb.toString();
     }
 
 }

@@ -35,6 +35,12 @@
             <action class="org.onlab.onos.cli.net.TopologyCommand"/>
         </command>
         <command>
+            <action class="org.onlab.onos.cli.net.PathListCommand"/>
+            <completers>
+                <ref component-id="deviceIdCompleter"/>
+            </completers>
+        </command>
+        <command>
             <action class="org.onlab.onos.cli.net.ClustersListCommand"/>
         </command>
         <command>