Project feasibility w/ Arduino?

Project feasibility w/ Arduino? I have a simple requirement that involves scanning a local or network folder on a PC. I need the Arduino to turn a digital pin high when a text "key" file of a particular name is written to a predetermined folder on the local PC or in network location. I would like for this to be in an autonomous mode without communication to a host PC program. Can this be done easily with an Arduino? The fewer lines of code the better.

I can't think of any really feasible way you could do this without a host PC program. Certainly not one that ran in a few lines of code. Hopefully someone else can prove me wrong though.

No matter how you slice it, some program is going to have to query the filesystem. There's communication right there. So, the answer depends on your definition of 'easily'. I can think of the possibility of having a daemon program on the PC looking for the file, and then raising DTR (or CTS) on a serial line, and detecting this with the Arduino, but then you're looking at using RS232, or maybe you can detect something like that over USB (I haven't looked at how serial over USB works at all). Might be if all you're looking for is one pin going high, the hardware interface can be much simpler. But Arduino pins aren't capable of taking RS232 lines directly.

What OS are you running?

I am running a Windows 7 enviornment, but have not ruled out Linux on a dedicated single board pc. However I am a complete Arduino and Linux newb.

Why does everybody say it requires a program on the pc side? With enough knowledge it's possible to implement a simplified version of the SMB protocol to do that. But, you will have to modify/add to the ethernet library to do this. It's not impossible.

Edit:
That would obviously require the ethernet board or the ethernet shield

robindegen:
Why does everybody say it requires a program on the pc side? With enough knowledge it's possible to implement a simplified version of the SMB protocol to do that. But, you will have to modify/add to the ethernet library to do this. It's not impossible.

Mainly because that's the most practical thing. A modern PC will already have all the software infrastructure in place for watching for a file. SMB libraries (if needed), etc. And it'll be more flexible, since the file in question could be on local storage, NFS, CFS, iSCSI, whatever, but once the filesystem is mounted, it's the same system call to check for whether a file is there, and the OS does the heavy lifting for you. inotify is already there on Linux. BSD and Mac have kqueue. YMMV, but I'd much rather toss together something in Perl or Python or even bash than attempt to construct SMB packets. And who's to say the the target PC is even running something that would talk SMB? This is what the OS is for -- to do things like isolate you from having to code down at that level.

i would suggest you to forget about the filesystem sharing facilities out there. Whatever if it’s SMB (Microsoft based), NFS (More of a Linux thing) or even AFP (Mac), the implementations are really heavy, specially if there is a layer of authentication.

i would start by thinking cross-platform (Will you always need to look for that file on the same PC operating system). Then based on that answer, either use a lightweight implementation of FTP (Yes, really, it’s all over TCP with very easy to understand specifications. Once you’ve established the connexion, it’s a matter of listing a given folder and looking in the result for a match), or maybe trying to implement a basic telnet client (Available on Windows, Mac, and any major distress as a very lightweight / small footprint daemon).

i hope this would help,
Pierre.