backup files before diving into code

bu.sh

#!/bin/sh

if [ $# -eq 0 ]; then
	echo "filename(s) to backup is missing. exiting."
	exit 1
fi

BACKUP_DATE=`date +%Y-%m-%d_%H:%M:%S`
BACKUP_EXT_PREFIX="backup"

for file in "$@"
	do
		if [ ! -f $file ]; then
			echo "\"$file\" does not exist. skipping."
			continue
		fi

		NEW_FILENAME="$file.$BACKUP_EXT_PREFIX.$BACKUP_DATE"
		cp $file $NEW_FILENAME 
		echo "\"$file\" has been backed up."
		FILES_TO_LIST="$FILES_TO_LIST $file* "
	done

if [ ${#FILES_TO_LIST} -lt 1 ]; then
	echo "no files have been backed up."
else
	ls -a $FILES_TO_LIST
fi