Best way to make a file writeable in c#

Question

I'm trying to set flag that causes the Read Only check box to appear when you right click \ Properties on a file.

Thanks!

Are you trying to make the file read only, per your question, or writeable (not read only), per your question title? — Lasse V. Karlsen, Jul 29 '09 at 18:19
This is a complicated issue on Win2k based OSes. There's the read-only attribute you can give a file, and there's also Write-permission which is granted via the "Permissions" tab. The former is just a suggestion, where as the latter is actually enforced by the operating system. — Armentage, Jul 29 '09 at 18:30
@Armentage I don't think it's that complicated. There's a clear distinction between file flags and NTFS permission sets, and this question clearly deals with the first case. — Rex M, Jul 30 '09 at 04:46

score 69 · Accepted Answer · edited Apr 21 '20 at 09:09

69

Two ways:

System.IO.FileInfo fileInfo = new System.IO.FileInfo(filePath);
fileInfo.IsReadOnly = true/false;

or

// Careful! This will clear other file flags e.g. `FileAttributes.Hidden`
File.SetAttributes(filePath, FileAttributes.ReadOnly/FileAttributes.Normal);

The IsReadOnly property on FileInfo essentially does the bit-flipping you would have to do manually in the second method.

edited Apr 21 '20 at 09:09

Yousha Aleayoub

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answered Jul 29 '09 at 18:09

Rex M

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Amazing how fast you can get an answer around here. I love this site! – JimDel Jul 29 '09 at 18:14
I didn't realize you could use the first method. Awesome! – Mike Cole Jul 29 '09 at 18:15
7

Note that this will effectively clear out the other flags on the same file at the same time. A hidden file will become visible, a system-file will become non-system, etc. – Lasse V. Karlsen Jul 31 '09 at 07:32
@Lasse the second method will, if someone does not understand how bit flags work. Thankfully you explained it already. – Rex M Jul 31 '09 at 13:50
2

The first method shortens to `new FileInfo(filePath) { IsReadOnly = false };`, which is neat! – joneberg Oct 17 '12 at 07:20

score 37 · Answer 2 · answered Jul 29 '09 at 18:23

To set the read-only flag, in effect making the file non-writeable:

File.SetAttributes(filePath,
    File.GetAttributes(filePath) | FileAttributes.ReadOnly);

To remove the read-only flag, in effect making the file writeable:

File.SetAttributes(filePath,
    File.GetAttributes(filePath) & ~FileAttributes.ReadOnly);

To toggle the read-only flag, making it the opposite of whatever it is right now:

File.SetAttributes(filePath,
    File.GetAttributes(filePath) ^ FileAttributes.ReadOnly);

This is basically bitmasks in effect. You set a specific bit to set the read-only flag, you clear it to remove the flag.

Note that the above code will not change any other properties of the file. In other words, if the file was hidden before you executed the above code, it will stay hidden afterwards as well. If you simply set the file attributes to .Normal or .ReadOnly you might end up losing other flags in the process.

score 1 · Answer 3 · edited Apr 21 '20 at 09:07

1

C# :

File.SetAttributes(filePath, FileAttributes.Normal);

File.SetAttributes(filePath, FileAttributes.ReadOnly);

edited Apr 21 '20 at 09:07

Yousha Aleayoub

4,532
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answered Jul 29 '09 at 18:09

score 0 · Answer 4 · answered Sep 14 '22 at 14:22

0

One-line answer (without changing other file attributes):

new FileInfo(filename).IsReadOnly = true/false;

answered Sep 14 '22 at 14:22

Udi Y

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Best way to make a file writeable in c#

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