安装onnx时报错：

cwd: /tmp/pip-install-z97qlhcj/onnx/
    Complete output (1 lines):
    Could not find "protoc" executable!
    ----------------------------------------
ERROR: Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.

解决方案：

pip install protobuf

sudo apt-get install protobuf-compiler libprotoc-dev

pip install onnx