May be it is, cron jobs will run in their own shell. So you can’t expect to see asdf on your console.
What you should try is
* * * * * echo asdf > somefile_in_your_home_directory_with_complete_path.log
Next check the file by doing a tail:
tail -f somefile_in_your_home_directory_with_complete_path.log
And if it’s not, check if the cron daemon itself is running or is down:
# pgrep crond
OR
# service crond status