How to make command to return to my ant build file

Have an ant file with a <exec> task; command does not return to my build file after executing the <exec> task. What do I do to to get the command back to my build file?
Thanks in advance.

Set spawn="true" in the exec task :
<exec spawn="true" ...

I had the same problem in my previous project, where I had to start a server, the spawn did not work.. I had a simple work around, I had a shell script that would run the process, all my ant script did was to execute this shell scripts