jzl@ubuntu:~/rosws$ rosrun Hello listenertest [rospack] Error: package 'Hello' not found

这错误的原因是找不到名为"Hello"的ROS包。请确保你在ROS环境中正确地创建和命名了该包，并且已经使其可用于ROS系统。你可以使用以下命令来检查ROS包路径是否包含你的包：`echo $ROS_PACKAGE_PATH`。如果你的包不在路径中，则可以使用以下命令将其添加到路径中：`export ROS_PACKAGE_PATH=/path/to/your/package:$ROS_PACKAGE_PATH`。

相关问题

rosparam load /home/jzl/catkin_ws/src/probot_description/urdf/probot_anno.xacro ERROR: global / can only be set to a dictionary

It seems like you are trying to load a parameter using the `rosparam load` command in ROS, but the parameter you are trying to load is not a dictionary type.

In ROS, the `rosparam` command is used to store and load parameters. Parameters are stored as a dictionary, which is a collection of key-value pairs.

To fix this error, you need to make sure that the parameter you are trying to load is in dictionary format. You can check the format of the parameter by opening the file containing the parameter and checking if it is a dictionary or not.

If the parameter is not in dictionary format, you can try converting it to a dictionary before loading it using the `yaml` library in Python. For example, you can use the following code to convert a YAML file to a dictionary:

import yaml

with open('parameter.yaml') as f:
    parameter_dict = yaml.load(f, Loader=yaml.FullLoader)

Then you can load the dictionary using the `rosparam` command:

rosparam set /my_parameter_name parameter_dict

DEPRECATION: Python 2.7 reached the end of its life on January 1st, 2020. Please upgrade your Python as Python 2.7 is no longer maintained. pip 21.0 will drop support for Python 2.7 in January 2021. More details about Python 2 support in pip can be found at https://pip.pypa.io/en/latest/development/release-process/#python-2-support pip 21.0 will remove support for this functionality. WARNING: The directory '/home/jzl/.cache/pip' or its parent directory is not owned or is not writable by the current user. The cache has been disabled. Check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag. Requirement already satisfied: numpy in /usr/lib/python2.7/dist-packages (1.13.3)

这是pip给出的多个警告信息。第一个警告提示你的Python版本已经到达了它的生命周期终点，建议你尽快升级Python。第二个警告提示pip在2021年1月将停止对Python 2.7的支持。第三个警告提示pip无法读写缓存目录，可能会影响包的安装和更新。你可以检查该目录的权限和所有者，并确保当前用户具有写入权限。如果使用sudo执行pip，可以考虑使用sudo的-H标志来解决该问题。最后一行提示numpy已经安装成功了，无需重复安装。