Working on examples.

Added new example to create xterms.
Other minor changes.

examples/xterms.py

@@ -0,0 +1,39 @@
+#!/usr/bin/python
+
+"Create a network and run an xterm (connected via screen) on each host."
+
+import os
+from subprocess import Popen
+from mininet import init, TreeNet, Cli, quietRun
+
+def makeXterm( node, title ):
+   "Run screen on a node, and hook up an xterm."
+   node.cmdPrint( 'screen -dmS ' + node.name )
+   cmd = 'xterm -title ' + title + ':' + node.name
+   cmd += ' -e screen -D -RR -S ' + node.name
+   return Popen( cmd.split( ' ' ) )
+
+def makeXterms( nodes, title ):
+   terms = []
+   for node in nodes:
+      if not node.execed:
+         terms += [ makeXterm( node, title ) ]
+   return terms
+
+def xterms( controllers, switches, hosts ):
+   terms = []
+   terms += makeXterms( controllers, 'controller' )
+   terms += makeXterms( switches, 'switch' )
+   terms += makeXterms( hosts, 'host' )
+   # Wait for completion
+   for term in terms:
+      os.waitpid( term.pid, 0 )
+   
+def treeXterms():
+   print "Running xterms on", os.environ[ 'DISPLAY' ]
+   network = TreeNet( depth=2, fanout=4, kernel=True )
+   network.run( xterms )
+      
+if __name__ == '__main__':
+   init()
+   treeXterms()