How do you set file permissions or access control lists (ACLs) in C#?

Question

Anubhav Kumar · Answer

To set file permissions or Access Control Lists (ACLs) in C#, you use classes from the
System.Security.AccessControl namespace.
Example: Grant Read and Write Permissions to a Specific User
using System.IO;
using System.Security.AccessControl;
using System.Security.Principal;
public class FilePermissionHelper
{
    public static void SetFilePermissions(string filePath, string userName)
    {
        FileSecurity fileSecurity = File.GetAccessControl(filePath);
        // Create a new rule granting read and write access
        FileSystemAccessRule accessRule = new FileSystemAccessRule(
            userName,
            FileSystemRights.Read | FileSystemRights.Write,
            AccessControlType.Allow
        );
        // Add the rule and apply it
        fileSecurity.AddAccessRule(accessRule);
        File.SetAccessControl(filePath, fileSecurity);
    }
}
Usage
string file = @"C:\secure\file.txt";
string user = @"DOMAIN\UserName"; // or use Environment.UserName
FilePermissionHelper.SetFilePermissions(file, user);
Key Concepts
Class
Purpose
FileSecurity
Represents the ACL for a file
FileSystemAccessRule
Defines access rules (who, what rights)
AccessControlType
Allow or Deny
FileSystemRights
Enum for specific rights (e.g. Read, Write, Modify, FullControl)
To Remove or Modify Permissions
Use RemoveAccessRule, ResetAccessRule, or SetAccessRule on the
FileSecurity object.
Notes
Your application needs permission to change ACLs (run as administrator if needed).Works on NTFS file systems where ACLs are supported.Use DirectorySecurity and Directory.SetAccessControl for folders.

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How do you set file permissions or access control lists (ACLs) in C#?

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1 Answers

Example: Grant Read and Write Permissions to a Specific User

Usage

Key Concepts

To Remove or Modify Permissions

Notes

Liked By

Class	Purpose
`FileSecurity`	Represents the ACL for a file
`FileSystemAccessRule`	Defines access rules (who, what rights)
`AccessControlType`	`Allow` or `Deny`
`FileSystemRights`	Enum for specific rights (e.g. Read, Write, Modify, FullControl)