for more ways to do it checkout http://askubuntu.com/questions/192798/reading-the-output-from-any-process-using-its-pid
Today I was run a long process from crontab. But I forget to set the output of the command. Checking with ps aux | grep command_name shows me the pid. After that I can do the following command to actually shows the stdout of the process. really cool right?
tail -f /proc/