启动Turtlesim，输入roscore命令，报错

Error:

Traceback (most recent call last):
  File "/opt/ros/indigo/lib/python2.7/dist-packages/roslaunch/__init__.py", line 257, in main
    write_pid_file(options.pid_fn, options.core, options.port)
  File "/opt/ros/indigo/lib/python2.7/dist-packages/roslaunch/__init__.py", line 110, in write_pid_file
    with open(pid_fn, "w") as f:
IOError: [Errno 13] Permission denied: '/home/hht/.ros/roscore-11311.pid'

Reason:

權限問題，試試　sudo chmod 777 -R ~/.ros/