Dotenv File Linter

#!/bin/bash
FILE=${1:-.env}
errors=0

while IFS= read -r line; do
  [[ -z "$line" || "$line" =~ ^# ]] && continue
  if ! echo "$line" | grep -qP "^[A-Z0-9_]+="; then
    echo "BAD KEY: $line"; ((errors++))
  fi
  key=$(echo "$line" | cut -d= -f1)
  val=$(echo "$line" | cut -d= -f2-)
  if [ -z "$val" ]; then
    echo "EMPTY VALUE: $key"; ((errors++))
  fi
done < "$FILE"

echo "$errors error(s) found in $FILE"
exit $errors