cURL in an exec()

I can do this; exec("curl -d \"name=myname&password=mypassword&btnsubmit=submit\" -s -o cdrlist.html https://theserver.com/list.html"); but why can't I do this exec("curl -d \"name=myname&password=mypassword&btnsubmit=submit\" -s -o ".$listline." https://theserver.com/download/ ".$listline.""); The only change is that I have now made the variable $listline available as there is a routine that steps through each file from the list. I can print the line out and it looks correct. Am I missing something? Thanks! Jay