RUBY

heroku logs

heroku logs --tail

heroku logs

# Display all logs live
heroku logs -t -a YOUR_APP_NAME

# Only display stdout of your app
heroku logs -t -s app -a YOUR_APP_NAME

check heroku logs

Go to the heroku logs bit of the heroku dashboard.

Or, run this in shell when you're in the heroku app directory:
heroku logs

Or, for real time web logs (like flask logs, if you know what I mean), type;
heorku logs --tail

write heroku logs

puts "Hello, logs!"