$ roscore

# 在catkin工作空间中
$ cd ~/catkin_ws
$ source ./devel/setup.bash

$ rosrun beginner_tutorials talker 
     # (C++)
$ rosrun beginner_tutorials talker.py 
  # (Python)

[INFO] [WallTime: 1314931831.774057]
 hello world 1314931831.77
[INFO] [WallTime: 1314931832.775497] 
hello world 1314931832.77
[INFO] [WallTime: 1314931833.778937] 
hello world 1314931833.78
[INFO] [WallTime: 1314931834.782059] 
hello world 1314931834.78
[INFO] [WallTime: 1314931835.784853]
 hello world 1314931835.78
[INFO] [WallTime: 1314931836.788106]
 hello world 1314931836.79

$ rosrun beginner_tutorials listener     # (C++)
$ rosrun beginner_tutorials listener.py  # (Python) 

[INFO] [WallTime: 1314931969.258941] /listener_17657_
1314931968795I heard hello world 1314931969.26
[INFO] [WallTime: 1314931970.262246] /listener_
17657_1314931968795I heard hello world 1314931970.26
[INFO] [WallTime: 1314931971.266348] /listener_
17657_1314931968795I heard hello world 1314931971.26
[INFO] [WallTime: 1314931972.270429] /listener_
17657_1314931968795I heard hello world 1314931972.27
[INFO] [WallTime: 1314931973.274382] /listener_
17657_1314931968795I heard hello world 1314931973.27
[INFO] [WallTime: 1314931974.277694] /listener_
17657_1314931968795I heard hello world 1314931974.28
[INFO] [WallTime: 1314931975.283708] /listener_
17657_1314931968795I heard hello world 1314931975.28