Silly question

Hello, I'm trying to run through an apache log file in an attempt to get all of the user agents. The question is how do I split the string?  I can't seem to find a workable delimiter.  Each section of the file is enclosed in quotes and that should be helpful, but it doesn't seem to be.  I can't seem to set the delimiter to '" "' I can't seem to find any good examples, either. I can't split on spaces, because the user agents generally have spaces in them. I was trying to use explode.  print_r(explode('" "', $line); Any help would be appreciated. thanks, Curtis