cmake 提到 CUDA_TOOLKIT_ROOT_DIR 作为 cmake 变量，而不是环境变量.这就是为什么当您将其放入 .bashrc 时它不起作用的原因.如果您查看 FindCUDA.cmake，它会清楚地说明:

cmake mentioned CUDA_TOOLKIT_ROOT_DIR as cmake variable, not environment one. That's why it does not work when you put it into .bashrc. If you look into FindCUDA.cmake it clearly says that:

如果前缀为 CUDA_TOOLKIT_ROOT_DIR，脚本将提示用户指定无法通过系统路径中 nvcc 的位置来确定并且需要指定给 find_package().要使用不同的已安装版本工具包在运行 cmake 之前设置环境变量 CUDA_BIN_PATH(例如 CUDA_BIN_PATH=/usr/local/cuda1.0 而不是默认的/usr/local/cuda)或在配置后设置 CUDA_TOOLKIT_ROOT_DIR.如果你改变值CUDA_TOOLKIT_ROOT_DIR，各种依赖路径的组件都会被搬迁.

The script will prompt the user to specify CUDA_TOOLKIT_ROOT_DIR if the prefix cannot be determined by the location of nvcc in the system path and REQUIRED is specified to find_package(). To use a different installed version of the toolkit set the environment variable CUDA_BIN_PATH before running cmake (e.g. CUDA_BIN_PATH=/usr/local/cuda1.0 instead of the default /usr/local/cuda) or set CUDA_TOOLKIT_ROOT_DIR after configuring. If you change the value of CUDA_TOOLKIT_ROOT_DIR, various components that depend on the path will be relocated.

因此将 CUDA_BIN_PATH 放入 .bashrc 或指定 CUDA_TOOLKIT_ROOT_DIR 到 cmake:

So put CUDA_BIN_PATH into .bashrc or specify CUDA_TOOLKIT_ROOT_DIR to cmake:

cmake -D CUDA_TOOLKIT_ROOT_DIR=/usr/local/cuda-5.5 ..