Fix broken python code that makes assumptions about /usr/bin/python.

fix_python_shebangs

#!/bin/sh
# Fix all shebangs of files in a directory which do not explicitly state the
# major version number of the Python interpreter, ie refer to /usr/bin/python
# and assume that it is 2.x (or 3.x, but most Python 3 projects already use
# /usr/bin/env python3).

echo "Explicit is better than implicit!

This will fix all shebangs referring to /usr/bin/python
in all files below the current directory.

THIS OPERATION IS RECURSIVE AND DESTRUCTIVE! USE A VCS!
"

read -p "Proceed? (y/n) " answer

case $answer in
    [yY])
        echo -n "Fixing shebangs..."
        grep -Rl '#!/usr/bin/python$' |\
            xargs sed -i 's#\(/usr/bin/\)python#\1env python2#'
        echo "done"
        exit 0
        ;;
    *)
        echo "Aborting."
        exit 1
        ;;
esac

don't you mean grep -Rl '#!/usr/bin/python$' * |\ xargs sed -i 's#\(/usr/bin/\)python#\1env python2#' ?