run a simple HTTP server using python 2 or 3 via command line using bash script

www.sh

#!/bin/bash
### purpose: run simple HTTP server in both Python2 and Python3
### note: set PYTHON and ARGS environment variables for control the behaviour

export PORT=${PORT:-8000}  # open http://localhost:8000/
export ARGS=${ARGS:-${PORT}}
export PYTHON=${PYTHON:-python}

echo "Running HTTP Server via [${PYTHON}]: "
${PYTHON} -VV -V --version || exit $?

echo "Command line arguments: [${ARGS}]..."
export PYTHON_MAJOR_VERSION=`${PYTHON} -c "import sys; print(sys.version_info.major)"`

if [[ "${PYTHON_MAJOR_VERSION}" == "2" ]]; then
   # in Python 2
   export HTTP_SERVER_MODULE="SimpleHTTPServer"
elif [[ "${PYTHON_MAJOR_VERSION}" == "3" ]]; then
   # in Python 3
   export HTTP_SERVER_MODULE="http.server"
else
   echo "Sorry: version of [$PYTHON] is not supported!"
   exit 1
fi

echo "Press Ctrl+C to exit."
exec ${PYTHON} -m ${HTTP_SERVER_MODULE:-ERROR_UNKNOWN_MODULE} ${ARGS}