Check which versions a Python file is valid syntax for

pycheck.sh

#!/bin/bash

#
# Script to check which versions of python a file is valid syntax for.
#
# The intention is to catch things like 'print' as a keyword (python2), type
# hints, f-strings or async that aren't valid on 3.5, or other new syntax such
# as pattern matching.
#
# This can be useful for identifying python2 files, and should give zero false
# positives for incompatibilities. However, it won't catch things like misssing
# imports or missing builtins, so it may be worth also searching for things
# like 'xrange' or using 'pylint --errors-only'.
#
# This uses a hardcoded array of Python executables 'PYTHON_EXES' to check
# against, which may need changing.
#

set -e
shopt -s globstar

PYTHON_EXES=(
    "$HOME/venv27/bin/python"
    "$HOME/venv35/bin/python3"
    "$HOME/venv36/bin/python3"
    "$HOME/venv37/bin/python3"
    "$HOME/venv38/bin/python3"
    "$HOME/venv39/bin/python3"
)

usage () {
    echo -n "\
Usage: $(basename "$0") [-h|--help] [FILE|DIR ...]

Wrapper around 'python3 -m py_compile' to check for invalid syntax for
different python versions.
"
    exit 0
}

get_python_version () {
    "$1" --version 2>&1 | grep -o -E "[2-4].[0-9]+"
}

CHECK_FILES=()

while [[ $# -gt 0 ]]; do
    case "$1" in
        -h | --help )
            usage
            ;;
        *)
            for path in "$@"; do
                if [[ -f $path ]]; then
                    CHECK_FILES+=("$path")
                else
                    py_files=(${path%/}/**/*.py)
                    if [[ -f ${py_files[0]} ]]; then
                        CHECK_FILES+=("${py_files[@]}")
                    fi
                fi
            done
            break
            ;;
    esac
done

if [[ ${#CHECK_FILES[@]} == 0 ]]; then
    CHECK_FILES=(./**/*.py)
fi

echo "Proceeding to check ${#CHECK_FILES[@]} files with ${#PYTHON_EXES[@]} python exes" >&2

for python_exe in "${PYTHON_EXES[@]}"; do
    python_version=$(get_python_version "$python_exe")
    rm "errors-$python_version.txt" 2>/dev/null || true
    rm "incompatible_files-$python_version.txt" 2>/dev/null || true
    touch "errors-$python_version.txt"
    touch "incompatible_files-$python_version.txt"
done

for file in "${CHECK_FILES[@]}"; do
    echo
    echo "$file"
    for python_exe in "${PYTHON_EXES[@]}"; do
        python_version=$(get_python_version "$python_exe")
        errors_file="errors-$python_version.txt"
        list_file="incompatible_files-$python_version.txt"
        if "$python_exe" -m py_compile "$file" 2>> "$errors_file"; then
            echo -n "  $python_version"
            # break  # May wish to break as soon as a valid version is found
        else
            echo "$file" >> "$list_file"
        fi
    done
    echo
done

echo
echo "See created files 'incompatible_files-<version>.txt' and 'errors-<version>.txt'" >&2