Permission Mirror is a VS Code extension that applies inheritance when new files or directories are created, ensuring they match the parent’s ownership and permission model. Existing files are not altered on save, so any intentional changes to permissions or group ownership remain intact.
Why?
By default, Linux only applies group ownership if the user’s active group matches. Permission Mirror bridges that gap by interpreting directory intent (g+s) and enforcing it automatically, so you don’t have to run chgrp manually.
Features
Mirrors parent directory permissions on file or directory creation.
Applies execute bits to files only if they are configured as auto‑executable (e.g. .sh).
Always mirrors execute bits for directories to allow traversal.
Enforces group ownership when parent has setgid.
Preserves g+s on new directories when parent has setgid.
Setup and Installation
Clone this repo:
git clone https://github.com/kryogeniks/PermissionMirror.git
cd PermissionMirror
Install dependencies:
npm install
Compile TypeScript:
npm run compile
Open the folder in VS Code and press F5 to launch an Extension Development Host, or run vsce package to build a .vsix and install it.
Usage
On file or directory creation, permissions are mirrored automatically.
Create a file inside a directory with the setgid bit set (chmod g+s dir).
If you’re a member of that directory’s group, the extension will automatically chgrp the file.
If not, the file is created normally without errors.
Example
Here’s how permissions are mirrored in practice:
Example: parent is root:www-data
Context
Permissions
Owner:Group
Parent
drwxr-s---
root:www-data
New file
-rw-r-----
user1:group2
New .sh file
-rwxr-x---
user1:group2
New directory
drwxr-s---
user1:group2
1 current user 2 directory's set-group, if applicable; otherwise active group
Example: parent is alice:dev
Context
Permissions
Owner:Group
Parent
drwxrwxr-x
alice:dev
New file
-rw-rw-r--
user1:group2
New .py file
-rwxrwxr-x
user1:group2
New directory
drwxrwxr-x
user1:group2
1 current user 2 current active group
Requirements
Unix-like OS (Linux, macOS).
User must be a member of the target group for enforcement to succeed.
Standard tools available: stat, chgrp.
Notes
No effect on Windows — the extension silently skips.
Lightweight utility for exploring group ownership automation in your workflow.
