Reactions To A Busy File

I just wanted to know if let's say you have a file called tempfile.dat and it is being used by dozens of parts of a script to transfer data, what happens if both scripts run at the same time and use the tempfile? will it throw a text file is busy error or will it patiently wait until a script is done using it before it uses it?Because if i send information to the tempfile, then close it, then reopen it again to transfer back the information, I don't want the other script to start using it in the middle of that sequence or the results will be catastrophic.Any info appreciated.

(scripts? C++ forums? just wondering) Well it's kind of weird. For some apps a busy error comes, for other ones, it goes straight for it. I believe a system busy error will happen. By the way, I never heard of requests for the same file stacked by systems, so in either case, you'll get a system busy or those catastrophic results.

what? tempfile.dat? if it is a script, then is C a script or at least can be used as script language? for all I know, C is a language that cannot be used as a script (not like VB that can be used as scripting)anyway, if you ask for a script language nearing C, then PHP will come to mind.