在 conda 环境下 pip install mpi4py 安装 mpi4py 库时出现编译报错，报错信息为：

 line 301: x86_64-conda_cos6-linux-gnu-cc: command not found
      failure.
      removing: _configtest.c _configtest.o
      error: Cannot compile MPI programs. Check your configuration!!!
      [end of output]
  
  note: This error originates from a subprocess, and is likely not a problem with pip.
  ERROR: Failed building wheel for mpi4py
Failed to build mpi4py
ERROR: Could not build wheels for mpi4py, which is required to install pyproject.toml-based projects

所以导致该错误的原因是

x86_64-conda_cos6-linux-gnu-cc: command not found

即没有找到 x86_64-conda_cos6-linux-gnu-cc。只需执行以下命令安装即可：

conda install gcc_linux-64

安装完成后重新执行 pip install mpi4py 即可完成安装。