fix stdin may not found when using in startup script

Author: ccloli

index.js

@@ -86,11 +86,16 @@ const init = (input) => {
 		}
 	};
 
-	process.stdin.setRawMode(true);
-	process.stdin.resume();
-	process.stdin.on('data', closeListener);
+	if (process.stdin) {
+		process.stdin.setRawMode(true);
+		process.stdin.resume();
+		process.stdin.on('data', closeListener);
 
-	console.log('Press ^R to reload, ^C or ^Z to exit');
+		console.log('Press ^R to reload, ^C or ^Z to exit');
+	}
+	else {
+		console.log(`Cannot listen to stdin, if you're using DNSProxy in startup script, try killing pid ${process.pid} to terminate`);
+	}
 };
 
 const printHelp = () => {