Serving any iFiles: sanitising user input

Thanks, certainly looks safer and it's a cleaner option than using the catch command. I'm happy with this solution since we have full control over the ifile names, and I assume there's not much risk of TCL interpreting them as anything other than strings anyway. I'm relatively new to TCL and started to worry that TCL injection might be a possibility. A quick search turned up only a couple options for sanity checking, either using regex (which is apparently inefficient) or using scan (which seemed pretty limited).