Git pre-commit hook for python code

pre-commit

#!/bin/sh

# requires py_compile and pycodestyle Python module

if git rev-parse --verify HEAD >/dev/null 2>&1
then
	against=HEAD
else
	# Initial commit: diff against an empty tree object
	against=4b825dc642cb6eb9a060e54bf8d69288fbee4904
fi

temp_dir=''
function tear_down {
	[ -d "$temp_dir" ] && rm -rf "$temp_dir"
}
trap tear_down EXIT

git diff --cached --name-only --diff-filter=d $against | egrep '\.py$' | while read file; do
	[ -z "$temp_dir" ] && {
		temp_dir=$(mktemp -d)
		[ -f setup.cfg ] && cp setup.cfg "$temp_dir"
	}
	temp_template="$temp_dir/$(basename "$file")"
	temp_template=${temp_template%.py}.XXXX.py
	temp_file=$(mktemp "$temp_template")
	git show :"$file" > "$temp_file"
	python -m py_compile "$temp_file"
	compile_status=$?
	if [ $compile_status -ne 0 ]; then
		echo ">>>> compilation failed for '$file' [stat=$compile_status]" >>/dev/stderr
		exit $compile_status
	fi
	temp_comp="${temp_file%.py}.pyc"
	[ -f "$temp_comp" ] && rm "$temp_comp"
	#pycodestyle --count "$temp_file" --first --format="$file"'@%(row)d,%(col)d: [%(code)s] %(text)s'
	# pycodestyle -qq --count "$temp_file" 2>> /dev/null
	pycodestyle -qq --statistics "$temp_file" >> /dev/stderr
	pep8_status=$?
	if [ $pep8_status -ne 0 ]; then
		echo ">>>> PEP8 failures for '$file' [stat=$pep8_status]" >>/dev/stderr
		# pycodestyle -qq --ignore="$PEP8_IGNORES" --statistics "$temp_file" >> /dev/stderr
		echo 'To see suggestions of fixes, run: autopep8 --verbose --diff "'$file'"'
		exit "$pep8_status"
	fi
	rm "$temp_file"
done