diff --git a/ubuntu/Dockerfile b/ubuntu/Dockerfile
index f3829734085701db9c205b61ef2cec06f255675d..667c1cdd72f7e2ec8955b513a0f669827d37795f 100644
--- a/ubuntu/Dockerfile
+++ b/ubuntu/Dockerfile
@@ -56,29 +56,28 @@ RUN apt-get update && \
         && \
     apt-get clean
 
-SHELL ["/bin/bash", "-c"]
-RUN apt-get update && \
+RUN /bin/bash -c "apt-get update && \
     apt-get install -y --no-install-recommends \
-        cuda-command-line-tools-${CUDA/./-} \
+        cuda-command-line-tools-\${CUDA/./-} \
         libcublas10=10.2.1.243-1 \ 
         libcublas-dev=10.2.1.243-1 \
-        cuda-nvrtc-${CUDA/./-} \
-        cuda-nvrtc-dev-${CUDA/./-} \
-        cuda-cudart-dev-${CUDA/./-} \
-        cuda-cufft-dev-${CUDA/./-} \
-        cuda-curand-dev-${CUDA/./-} \
-        cuda-cusolver-dev-${CUDA/./-} \
-        cuda-cusparse-dev-${CUDA/./-} \
-        libcudnn7=${CUDNN}+cuda${CUDA} \
-        libcudnn7-dev=${CUDNN}+cuda${CUDA} \
+        cuda-nvrtc-\${CUDA/./-} \
+        cuda-nvrtc-dev-\${CUDA/./-} \
+        cuda-cudart-dev-\${CUDA/./-} \
+        cuda-cufft-dev-\${CUDA/./-} \
+        cuda-curand-dev-\${CUDA/./-} \
+        cuda-cusolver-dev-\${CUDA/./-} \
+        cuda-cusparse-dev-\${CUDA/./-} \
+        libcudnn7=\${CUDNN}+cuda\${CUDA} \
+        libcudnn7-dev=\${CUDNN}+cuda\${CUDA} \
         && \
-    find /usr/local/cuda-${CUDA}/lib64/ -type f -name 'lib*_static.a' -not -name 'libcudart_static.a' -delete && \
+    find /usr/local/cuda-\${CUDA}/lib64/ -type f -name 'lib*_static.a' -not -name 'libcudart_static.a' -delete && \
     rm /usr/lib/x86_64-linux-gnu/libcudnn_static_v7.a && \
     apt-get install -y --no-install-recommends \
-        libnvinfer${LIBNVINFER_MAJOR_VERSION}=${LIBNVINFER}+cuda${CUDA} \
-        libnvinfer-dev=${LIBNVINFER}+cuda${CUDA} \
-        libnvinfer-plugin-dev=${LIBNVINFER}+cuda${CUDA} \
-        libnvinfer-plugin${LIBNVINFER_MAJOR_VERSION}=${LIBNVINFER}+cuda${CUDA}
+        libnvinfer\${LIBNVINFER_MAJOR_VERSION}=\${LIBNVINFER}+cuda\${CUDA} \
+        libnvinfer-dev=\${LIBNVINFER}+cuda\${CUDA} \
+        libnvinfer-plugin-dev=\${LIBNVINFER}+cuda\${CUDA} \
+        libnvinfer-plugin\${LIBNVINFER_MAJOR_VERSION}=\${LIBNVINFER}+cuda\${CUDA}"
 
 RUN apt-get update && \
     apt-get install -y \