How to Create a Shared Directory for All Users in Linux?

When multiple users need access to the same set of directories or files, we need to create shared folders in Linux. Linux uses users and groups with specific permission levels to enable secure data sharing. Below are the steps to create shared folders where multiple users can read and update files.

Step 1: Create the Shared Directory

First, create the directory that will be shared. The -p flag creates the directory and ignores errors if it already exists ?

sudo mkdir -p /bigproject/sharedFolder

Step 2: Create a User Group

Create a user group that will contain all users who need access to the shared folder ?

sudo groupadd SharedUsers

Step 3: Set Group Ownership and Permissions

Assign the new group as owner of the shared folder and set appropriate permissions. The 2775 permission includes the setgid bit, ensuring new files inherit the group ownership ?

sudo chgrp -R SharedUsers /bigproject/sharedFolder
sudo chmod -R 2775 /bigproject/sharedFolder

Understanding the Permission 2775

Step 4: Add Users to the Group

Add existing users to the SharedUsers group so they can access the shared folder ?

sudo usermod -a -G SharedUsers user1
sudo usermod -a -G SharedUsers user2

For new users, create them and add to the group in one command ?

sudo useradd -G SharedUsers user3

Step 5: Verify the Setup

Check the directory permissions and group membership to ensure everything is configured correctly ?

ls -la /bigproject/sharedFolder
groups user1

Testing the Shared Directory

Users should now be able to create and modify files in the shared directory. When a user creates a file, it will automatically belong to the SharedUsers group, making it accessible to all group members ?

# As user1
echo "Test content" > /bigproject/sharedFolder/testfile.txt
ls -la /bigproject/sharedFolder/testfile.txt

Conclusion

Creating a shared directory in Linux involves creating a group, setting proper permissions with the setgid bit (2775), and adding users to the group. The setgid bit ensures new files automatically inherit group ownership, maintaining proper access control for all shared content.