Updated build script

src/build.sh

@@ -4,18 +4,22 @@ set -e  # Any error will cause the script to fail
 # See https://dev.intelrealsense.com/docs/compiling-librealsense-for-linux-ubuntu-guide
 
 # Install dependencies
-sudo apt-get install libssl-dev libusb-1.0-0-dev libudev-dev pkg-config libgtk-3-dev
-sudo apt-get install git wget cmake build-essential
-sudo apt-get install libglfw3-dev libgl1-mesa-dev libglu1-mesa-dev at
+sudo apt-get install -y libssl-dev libusb-1.0-0-dev libudev-dev pkg-config libgtk-3-dev
+sudo apt-get install -y git wget cmake build-essential
+sudo apt-get install -y libglfw3-dev libgl1-mesa-dev libglu1-mesa-dev at
 
 # Build the RealSense SDK
-cd librealsense
-mkdir -p build
-cd build
-cmake .. -DFORCE_LIBUVC=true -DCMAKE_POSITION_INDEPENDENT_CODE=true -DBUILD_EXAMPLES=true -DBUILD_GRAPHICAL_EXAMPLES=true -DBUILD_GLSL_EXTENSIONS=true -DBUILD_TOOLS=true -DBUILD_WITH_OPENMP=true -DBUILD_SHARED_LIBS=true -DCMAKE_BUILD_TYPE=Release 
-make -j8
-sudo make install
-cd ../..
+if [ ! -f /usr/local/lib/librealsense2.so ]
+then
+  echo "Compiling RealSense SDK. This can take ~45 minutes..."
+  cd librealsense
+  mkdir -p build
+  cd build
+  cmake .. -DFORCE_LIBUVC=true -DCMAKE_POSITION_INDEPENDENT_CODE=true -DBUILD_EXAMPLES=true -DBUILD_GRAPHICAL_EXAMPLES=true -DBUILD_GLSL_EXTENSIONS=true -DBUILD_TOOLS=true -DBUILD_WITH_OPENMP=true -DBUILD_SHARED_LIBS=true -DCMAKE_BUILD_TYPE=Release
+  make -j8
+  sudo make install
+  cd ../..
+fi
 
 # Build our FFI wrappers
 make clean