Tomcat 7 Ubuntu Server 12.04 LTS:
tail -f /var/log/tomcat7/catalina.out
locate catalina.out and find out where is your catalina out. Because it depends.
locate catalina.out
If there is several, look at their sizes: that with size 0 are not what you want.
Sometimes it is located in different places. It depends on the server.You can use find to find it:
find
find / -name catalina.out
If you encounter permission issues, add sudo to the command:
sudo
sudo find / -name catalina.out
That's all.
I hope this helps