Save all the previous copies of a config file without duplicates

save.sh

# Bash function
#
# Usage: save foo.bar
# - creates a file like foo.bar.d41d8cd,
# - overwrites previous copy if identical,
# - preserves other previous versions with very high probability
#
save() {
  file=$1
  if [[ -f "$file" ]]; then
    hash=$(md5sum "$file" | cut -c1-7)
    cp "$file" "$file"."$hash"
  fi
}