Easiest way to read text file which is locked by another application

Question

I've been using File.ReadAllText() to open a CSV file, but every time I forget to close the file in Excel, the application throws an exception because it can't get access to the file.

(Seems crazy to me, I mean the READ in ReadAllText seems pretty clear)

I know that there is File.Open with all the bells and whistles, but is there an 'intermediate' method which doesn't involve messing around with buffers and char arrays?

score 62 · Accepted Answer · edited Oct 06 '14 at 19:42

62

I think you just want the following:

using (var fileStream = new FileStream("foo.bar", FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
using (var textReader = new StreamReader(fileStream))
{
    var content = textReader.ReadToEnd();
}

The FileAccess.Read parameter is what is important, to indicate that you only want to read the file. Of course, even to do this, the file must have been opened by Excel in read-share mode (see the FileShare enum in .NET). I haven't tested, so I can't guarantee that Excel does this, though I would expect it does.

edited Oct 06 '14 at 19:42

Kingpin2k

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answered Sep 07 '09 at 12:26

Noldorin

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Thanks, what is the shortest thing I can put between the {} to get the whole string out of the file? (I did say I was lazy) – Benjol Sep 07 '09 at 13:25
@Noldorin, thanks. That was the missing link. I looked at all the methods available on FileStream, couldn't understand. – Benjol Sep 07 '09 at 14:02
4

@Noldorin: For info, I got round to trying it, you have to include the FileShare.ReadWrite argument to get it to work with Excel. – Benjol Sep 08 '09 at 07:05
@Benjol: Ah, that makes sense I guess. Good to know anyway. – Noldorin Sep 08 '09 at 11:30

score 0 · Answer 2 · answered Sep 07 '09 at 12:24

0

If you want to specify file sharing flags in order to open a file that's in use, you're stuck with File.Open().

answered Sep 07 '09 at 12:24

Philippe Leybaert

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It's Excel that's opening the file, so the OP can't control this. He can only hope Excel does open it in read-share mode, and open it read-only himself. – Noldorin Sep 07 '09 at 12:27

Easiest way to read text file which is locked by another application

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