sudo: emcmake: command not found

I am trying to install [opencv js using the instructions in this link](https://docs.opencv.org/3.4/d4/da1/tutorial_js_setup.html). I've followed the [emscripten sdk instructions given here](https://emscripten.org/docs/getting_started/downloads.html), and am trying to run ``emcmake python ./opencv/platforms/js/build_js.py build_js``. This returns the following error:

```
configure: python ./opencv/platforms/js/build_js.py build_js
Args: Namespace(build_dir='build_js', build_doc=False, build_flags=None, build_loader=False, build_perf=False, build_test=False, build_wasm=False, build_wasm_intrin_test=False, clean_build_dir=False, cmake_option=None, config='/home/mkocherov/opencv/platforms/js/opencv_js.config.py', config_only=False, disable_wasm=False, emscripten_dir='/home/mkocherov/emsdk/upstream/emscripten', enable_exception=False, opencv_dir='/home/mkocherov/opencv', simd=False, skip_config=False, threads=False)

Check dir /home/mkocherov/build_js (create: True, clean: False)
Check dir /home/mkocherov/opencv (create: False, clean: False)
Check dir /home/mkocherov/emsdk/upstream/emscripten (create: False, clean: False)
=====
===== Config OpenCV.js build for default target
=====
Executing: ['cmake', '-DPYTHON_DEFAULT_EXECUTABLE=/usr/bin/python', '-DENABLE_PIC=FALSE', '-DCMAKE_BUILD_TYPE=Release', "-DCMAKE_TOOLCHAIN_FILE='/home/mkocherov/emsdk/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake'", "-DCPU_BASELINE=''", "-DCPU_DISPATCH=''", '-DCV_TRACE=OFF', '-DBUILD_SHARED_LIBS=OFF', '-DWITH_1394=OFF', '-DWITH_ADE=OFF', '-DWITH_VTK=OFF', '-DWITH_EIGEN=OFF', '-DWITH_FFMPEG=OFF', '-DWITH_GSTREAMER=OFF', '-DWITH_GTK=OFF', '-DWITH_GTK_2_X=OFF', '-DWITH_IPP=OFF', '-DWITH_JASPER=OFF', '-DWITH_JPEG=OFF', '-DWITH_WEBP=OFF', '-DWITH_OPENEXR=OFF', '-DWITH_OPENGL=OFF', '-DWITH_OPENVX=OFF', '-DWITH_OPENNI=OFF', '-DWITH_OPENNI2=OFF', '-DWITH_PNG=OFF', '-DWITH_TBB=OFF', '-DWITH_TIFF=OFF', '-DWITH_V4L=OFF', '-DWITH_OPENCL=OFF', '-DWITH_OPENCL_SVM=OFF', '-DWITH_OPENCLAMDFFT=OFF', '-DWITH_OPENCLAMDBLAS=OFF', '-DWITH_GPHOTO2=OFF', '-DWITH_LAPACK=OFF', '-DWITH_ITT=OFF', '-DWITH_QUIRC=ON', '-DBUILD_ZLIB=ON', '-DBUILD_opencv_apps=OFF', '-DBUILD_opencv_calib3d=ON', '-DBUILD_opencv_dnn=ON', '-DBUILD_opencv_features2d=ON', '-DBUILD_opencv_flann=ON', '-DBUILD_opencv_gapi=OFF', '-DBUILD_opencv_ml=OFF', '-DBUILD_opencv_photo=ON', '-DBUILD_opencv_imgcodecs=OFF', '-DBUILD_opencv_shape=OFF', '-DBUILD_opencv_videoio=OFF', '-DBUILD_opencv_videostab=OFF', '-DBUILD_opencv_highgui=OFF', '-DBUILD_opencv_superres=OFF', '-DBUILD_opencv_stitching=OFF', '-DBUILD_opencv_java=OFF', '-DBUILD_opencv_js=ON', '-DBUILD_opencv_python2=OFF', '-DBUILD_opencv_python3=OFF', '-DBUILD_EXAMPLES=OFF', '-DBUILD_PACKAGE=OFF', '-DBUILD_TESTS=OFF', '-DBUILD_PERF_TESTS=OFF', '-DBUILD_DOCS=OFF', '-DWITH_PTHREADS_PF=OFF', '-DCV_ENABLE_INTRINSICS=OFF', '-DBUILD_WASM_INTRIN_TESTS=OFF', "-DCMAKE_C_FLAGS='-s USE_PTHREADS=0 '", "-DCMAKE_CXX_FLAGS='-s USE_PTHREADS=0 '", '/home/mkocherov/opencv']
Traceback (most recent call last):
File "./opencv/platforms/js/build_js.py", line 279, in
builder.config()
File "./opencv/platforms/js/build_js.py", line 192, in config
execute(cmd)
File "./opencv/platforms/js/build_js.py", line 25, in execute
raise Fail("Execution failed: %d / %s" % (e.errno, e.strerror))
__main__.Fail: Execution failed: 13 / Permission denied
```
However, running ``sudo emcmake python ./opencv/platforms/js/build_js.py build_js`` returns ``sudo: emcmake: command not found``. I am using Windows 10 with the Ubuntu 20.04 terminal, and I have added the emcmake env variables to my PATH, which I have checked.