Linux File Permissions
A Guide to Understanding and Managing File Permissions
This article provides a comprehensive guide to understanding and managing Linux file permissions, covering rwx permissions, changing ownership using chown and chmod, and a hands-on example for secure access configuration.
Linux File Permissions
Understanding rwx permissions
Linux file permissions control access to files and directories. They use a three-character code for owner, group, and others: read (r), write (w), and execute (x).
rwx rwx rwx # Owner, Group, OthersDo You Know? The numerical equivalent of rwx is 7 (4+2+1).
Changing ownership
chown
The chown command changes the owner and/or group of a file or directory.
chown owner:group file_or_directoryImportant Note: You need appropriate privileges (usually root) to change ownership.
chmod
The chmod command changes the permissions of a file or directory. You can use either symbolic or octal notation.
Avoid This: Avoid overly permissive settings (e.g., 777) unless absolutely necessary.
Hands-on: Configuring permission for secure access
Let's create a file and set appropriate permissions:
- Create a file:
touch myfile.txt - Check permissions:
ls -l myfile.txt - Change owner:
chown john:users myfile.txt - Change permissions:
chmod 640 myfile.txt - Verify changes:
ls -l myfile.txt
This example sets the owner to "john", group to "users", and permissions to read/write for the owner, read-only for the group, and no access for others.
Summary
- Linux permissions control access via read, write, and execute.
chownchanges file ownership.chmodalters file permissions using symbolic or octal notations.- Secure configurations prioritize least privilege.