aci-trailing-newline

#!/bin/sh -u

NAME="aci-trailing-newline"



print_usage() {
	echo "Usage: ${NAME} -n file"
	echo "       ${NAME} -1 file"
	echo "       ${NAME} -v"
	echo
	echo "Validates if a file has at least 1 or exactly only 1 trailing newline."
	echo "Returns 0, if condition is met, otherwise > 0"
	echo
	echo " -n     Must have at least 1 trailing newline at the end of the file."
	echo " -1     Must have exactly only 1 trailing newline at the end of the file."
	echo " -v     Show version"
	exit 1
}
print_version() {
	echo "${NAME} v0.1 (2016-08-21)"
	echo "Written by cytopia <cytopia@everythingcli.org>"
	echo "https://github.com/cytopia"
}

if [ "${#}" = "1" ] && [ "${1}" = "-v" ]; then
	print_version
	exit 0
fi

if [ "${#}" != "2" ]; then
	print_usage
	exit 1
fi
if [ "${1}" != "-n" ] && [ "${1}" != "-1" ]; then
	print_usage
	exit 1
fi

OPTION="${1}"
FILE="${2}"

#
# Validate file
#
if [ ! -f "${FILE}" ]; then
	echo "No such file: ${FILE}"
	exit 1
fi
if [ ! -r "${FILE}" ]; then
	echo "Cannot read file: ${FILE}"
	exit 1
fi



# No trailing newline at the end of the file
if ! tail -c 1 "${FILE}" | grep -qE "^$"; then
	exit 2
fi


# Check if only 1 trailing newline
if [ "${OPTION}" = "-1" ]; then

	# At least two newlines at the end of the file
	if tail -c 2 "${FILE}" | grep -qE "^$"; then
		exit 3
	fi

fi

exit 0