Shell Programs

I am making an application that will wake up every 10 minutes to print labels. I will read a label table to get all the info I need to print. The info in the table will determine what type of label needs to be printed. Each different type of label is printed from a different application. So... when I get the info I am thinking I should shell the application I want to run and pass it the data. I am worried though that the program will shell an applicaion and then 10 minutes later run again while the first instance is still going. Any ideas on how I can get control of the shelled application and sense that it has finished? I dont need to use shells if there is a better way.

Have a look at this post

Thanks, that should do the trick.