Avoid shortening an already shortened url

url.shortme.sh

@@ -52,6 +52,13 @@ fi
 
 [ "${debug}" -eq "0" ] && printf "${c_magentab}%-6b${c_reset}\n" "DEBUG − Get URL : URL to be shortened : ${url_to_short}"
 # ]]]
+# Ensure the URL wasn't already shortened [[[
+if printf -- '%s' "${url_to_short}" | grep -q -E -- "${null_service_url}"
+then
+	printf "${c_redb}%b${c_reset}\n" "Error : The url to be shortened (${url_to_short}) already seems to comes from the 0x0 service (${null_service_url})."
+	exit 1
+fi
+# ]]]
 
 # shorten URL
 result=$(curl -sF"shorten=${url_to_short}" "${null_service_url}")