sudo command to gain temporary root privileges or by modifying file permissions with chmod and chown. These methods allow you to read, write, or execute files outside your own user context. Understanding Linux file permission structures is essential for maintaining system security while sharing data between accounts.
Understanding Home Directory Permissions
In Ubuntu and most Linux distributions, every user has a dedicated home directory located under/home/username. By default, these directories are configured with strict permissions to protect user privacy and data integrity. The standard permission set for a home directory is typically 700, which means only the owner (the user) has read, write, and execute rights. Other users, including those in the same group or the general public, have no access at all.
This security model prevents unauthorized users from viewing sensitive files such as configuration dot-files, SSH keys, or personal documents. However, there are legitimate scenarios where an administrator or a different user needs to access these folders. For instance, troubleshooting application issues, recovering lost data, or managing shared project files may require crossing these permission boundaries. It is important to note that simply knowing the username is not enough; you must also have the appropriate system-level authorization.
If you encounter similar permission hurdles when dealing with web server directories, you might find our guide on Ubuntu 20.04: Permission Error when Writing to /var/www/html helpful, as the underlying concepts of user ownership and group permissions are very similar.
Method 1: Using Sudo for Temporary Access
The most common and straightforward way to access another user's home folder is by using thesudo command. This utility allows a permitted user to execute a command as the superuser or another user, as specified by the security policy. When you prefix a command with sudo, you are essentially asking the system to run that specific action with root privileges.
To list the contents of another user's home directory, you can use the following command structure:
sudo ls -la /home/other_usernamels lists files, -la shows all files including hidden ones in long format, and /home/other_username is the path to the target directory. You will be prompted to enter your own password, not the other user's password. Once authenticated, the command executes with root privileges, bypassing the standard 700 restriction.
You can also copy files from their home directory to yours using sudo cp. For example:
sudo cp /home/other_username/document.txt /tmp/Method 2: Modifying Permissions with Chmod and Chown
For more persistent access, you may need to alter the file permissions or ownership directly. This approach involves changing who owns the files or what access rights are granted to groups and others. Use caution with this method, as improper changes can expose sensitive data. To change the ownership of a file or directory to your current user, use thechown command:
sudo chown your_username:your_group /home/other_username/some_folderyour_username and your_group with your actual credentials. This makes you the new owner, granting you full control over the specified items.
Alternatively, if you want to grant read and write access to everyone without changing ownership, you can use chmod:
sudo chmod 755 /home/other_username/some_folder755 gives the owner full access, while the group and others get read and execute permissions. Note that execute permission on a directory is required to enter it, even if you only intend to read its contents. If you need to recursively apply these changes to all files within a directory, add the -R flag to both commands.
Best Practices for Secure Access
While gaining access is technically simple, it is crucial to follow best practices to maintain system security. Avoid setting world-writable permissions (777) unless absolutely necessary, as this allows any user on the system to modify those files. Instead, prefer changing ownership or adding specific users to a shared group.
Creating a shared group is a cleaner solution for collaborative environments. You can create a group, add both users to it, and then change the group ownership of the directory. Then, set permissions to 770, allowing only members of that group to access the directory. This minimizes exposure to the rest of the system.
Always verify your actions by checking the permissions after making changes using ls -l. If you are working with network shares or external drives, remember that mounting options can also affect access, much like how we handle local file systems. If you face issues with external storage or virtual machines affecting file accessibility, refer to our article on Ubuntu 22.04 VM on KVM/virt-manager Not Connecting to Internet for broader troubleshooting contexts involving system resources.
Frequently Asked Questions
Why can't I see my files in the GUI file manager?
The graphical file manager respects the same Unix permission bits as the terminal. If the directory is owned by another user with 700 permissions, the GUI will show "Permission Denied" because your user account lacks the necessary rights to traverse the directory.
Is it safe to give my password to someone else to access my files?
No, you should never share your password. Instead, use sudo yourself if you have administrative rights, or ask the system administrator to modify the permissions for you. Sharing passwords compromises the entire security model of the operating system.
How do I restore the original permissions after making changes?
You can revert changes by running sudo chown original_owner:original_group /path/to/directory and sudo chmod 700 /path/to/directory. Always keep track of the original owner before making bulk changes.
Can I access another user's files if I am not in the sudoers group?
No. Without sudo privileges or being the root user, you cannot override the default restrictive permissions of another user's home directory. You would need an administrator to grant you elevated privileges.
What if the files are encrypted with eCryptfs?
If the user's home directory is encrypted, accessing the raw files on disk will result in garbled data. You must decrypt the directory first, which typically requires the user's login password and active session, or specific cryptographic keys stored securely.