C# make file read/write from readonly

Question

If File.SetAttributes("C:\\myFile.txt", FileAttributes.ReadOnly); sets a file as read only, how do I set it back to read/write if I need to?

I suspect it would be FileAttributes.Normal however will this change any other properties of the file? There isn't an awfully descriptive note on the MSDN site...

The file is normal and has no other attributes set. This attribute is valid only if used alone.

Thanks

score 54 · Accepted Answer · answered Nov 10 '11 at 14:48

54

To remove just the ReadOnly attribute, you'd do something like this:

File.SetAttributes("C:\\myfile.txt", File.GetAttributes("C:\\myfile.txt") & ~FileAttributes.ReadOnly);

This will remove the ReadOnly attribute, but preserve any other attributes that already exist on the file.

answered Nov 10 '11 at 14:48

matt

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I'm guessing `~` reverses the attribute? – Thomas Clayson Nov 10 '11 at 14:51
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Pretty much - the `~` operator returns a bitwise complement of a given value. Semantically, what the above says is, "Set the attributes of file `myfile.txt` to the attributes of `myfile.txt` *except for the ReadOnly attribute*." – matt Nov 10 '11 at 14:59
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If instantiating a `FileInfo` object on your file is an option for you, you can then simply set its `IsReadOnly` property. http://msdn.microsoft.com/en-us/library/system.io.fileinfo.aspx – Frédéric Jun 17 '14 at 18:12
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And if you want to make the file ReadOnly (or assign any other attribute), you need to use | instead of &. For example: `File.SetAttributes(path, File.GetAttributes(path) | FileAttributes.ReadOnly);` – SepehrM Jul 03 '14 at 12:51

score 20 · Answer 2 · edited Jun 19 '18 at 16:53

20

File.SetAttributes replaces ALL attributes on the file.

The proper way to set and remove attributes is to first get the attributes, apply changes, and set them.

e.g.

var attr = File.GetAttributes(path);

// set read-only
attr = attr | FileAttributes.ReadOnly;
File.SetAttributes(path, attr);

// unset read-only
attr = attr & ~FileAttributes.ReadOnly;
File.SetAttributes(path, attr);

edited Jun 19 '18 at 16:53

Gary

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answered Nov 10 '11 at 14:50

Joe

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score 3 · Answer 3 · answered Jul 19 '18 at 20:56

I understand this is very late, but I wanted to share my solution hoping it helps others. I needed something similar and the way I accomplished was by setting the IsReadOnly property on FileInfo.

    private void UnsetReadOnlyAttribute(string filePathWithName)
    {
        FileInfo fileInfo = new FileInfo(filePathWithName);
        if (fileInfo.IsReadOnly)
        {
            fileInfo.IsReadOnly = false;
        }
    }

C# make file read/write from readonly

3 Answers3

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