Python wrapper to select the best interpreter available in the system

python.sh

#!/usr/bin/env bash

################################################################################
# Python Wrapper
# ------------------------------------------------------------------------------
# Author:            Joao Carmo
# License:                  MIT
# ------------------------------------------------------------------------------
# This wrapper script will test each available Python interpreter in the system
# to find the one which has the most critical modules installed and then execute
# the Python code
################################################################################

# Settings
pythons=('python' 'python2' 'python3') # Pythons list, accepts absolute paths
modules=('ssl')                        # Python modules list to test
py_script='my_script.py'               # Python code to execute if valid

# Debug function for verbose execution
function debug_print {
  if [ "$PY_DEBUG" = "true" ]; then
    echo "$1"
  fi
}

# Main loop
for py in ${pythons[@]}; do
  debug_print "testing for $py"
  py_exec=`which $py`
  exit_code=$?
  if [ $exit_code -eq 0 ]; then
    debug_print "$py exists in $py_exec"
    if [ -f $py_exec ]; then
      debug_print "$py_exec is a file"
      if [ -x $py_exec ]; then
        debug_print "$py_exec is executable"
        should_exec=0
        for mod in ${modules[@]}; do
          test=`$py_exec -c "import $mod" >/dev/null 2>&1`
          test_exit_code=$?
          if [ $test_exit_code -eq 0 ]; then
            debug_print "$py_exec has '$mod' support"
          else
            debug_print "$py_exec has no '$mod' support"
            should_exec=$(($should_exec + 1))
          fi
        done
        if [ $should_exec -eq 0 ]; then
          exec $py_exec "`python -c "import os;print(os.path.dirname(os.path.realpath('$0')))"`/$py_script" "$@"
        fi
      fi
    fi
  fi
done

# If no valid interpreter is found
echo "ERROR: No appropriate 'python' interpreter found" >&2
exit 1