node-apn logs is not getting stored in file

I need to debug the node-apn (some pushes are getting lost), so i need to analyze node-apn logs. Therefore, i want to store node-apn logs in a file.

What i have tried

I have enabled the node-apn logs and they are appearing on my console. Now, i am running following commands to start the server but i could not see node-apn logs in the file. I can see application logs (generated by winston) in file.

sudo node app.js test >> /home/gaurav/temp.txt
sudo node app.js test | tee /home/gaurav/temp.txt

Can anybody suggest how to achieve this.