Running Rails 5.0.1 rake tasks without depreciation messages in cron

crontab.sh

# This triple redirection allows filtering STDERR by removing depreciation messages
# The second grep allows removing empty lines (which might trigger an email on some server)

cd /home/appname/www/current && (RAILS_ENV=production bundle exec rake myapp:mytask 3>&1 1>&2 2>&3 | grep -v 'is deprecated' ) 3>&1 1>&2 2>&3 | grep -v ''

# You can also log STDOUT to a log file

cd /home/appname/www/current && ((RAILS_ENV=production bundle exec rake myapp:mytask 3>&1 1>&2 2>&3 | grep -v 'is deprecated' ) 3>&1 1>&2 2>&3 | grep -v '') >> /home/appname/www/shared/log/taskoutput.log