Mac fix for sed -r and date --date

Author: Intyre

installer.sh

@@ -55,12 +55,17 @@ done
 VERSION_DATA=$(download_file "http://www.pocketmine.net/api/?channel=$CHANNEL")
 
 VERSION=$(echo "$VERSION_DATA" | grep '"version"' | cut -d ':' -f2- | tr -d ' ",')
-BASE_VERSION=$(echo "$VERSION" | sed -r 's/([A-Za-z0-9_\.]*).*/\1/')
 BUILD=$(echo "$VERSION_DATA" | grep build | cut -d ':' -f2- | tr -d ' ",')
 API_VERSION=$(echo "$VERSION_DATA" | grep api_version | cut -d ':' -f2- | tr -d ' ",')
 VERSION_DATE=$(echo "$VERSION_DATA" | grep '"date"' | cut -d ':' -f2- | tr -d ' ",')
-VERSION_DATE_STRING=$(date --date="@$VERSION_DATE")
 VERSION_DOWNLOAD=$(echo "$VERSION_DATA" | grep '"download_url"' | cut -d ':' -f2- | tr -d ' ",')
+if [ "$(uname -s)" == "Darwin" ]; then
+	BASE_VERSION=$(echo "$VERSION" | sed -E 's/([A-Za-z0-9_\.]*).*/\1/')
+	VERSION_DATE_STRING=$(date -j -f "%s" $VERSION_DATE)
+else
+	BASE_VERSION=$(echo "$VERSION" | sed -r 's/([A-Za-z0-9_\.]*).*/\1/')
+	VERSION_DATE_STRING=$(date --date="@$VERSION_DATE")
+fi
 
 if [ "$VERSION" == "" ]; then
 	echo "[ERROR] Couldn't get the latest PocketMine-MP version"