/usr/bin/setup_vars_opencv4.sh: line 3: dirname: command not found /usr/bin/setup_vars_opencv4.sh: line 3: cd: null directory Setting vars for OpenCV 4.12.0 Append PYTHONPATH: /python_loader_is_not_installed /usr/bin/setup_vars_opencv4.sh: line 18: exec: -h: invalid option exec: usage: exec [-cl] [-a name] [command [argument ...]] [redirection ...]