Linux file systems and permissions are a critical component of the Linux operating system. Understanding how they work is essential to successfully managing and securing your Linux environment.
In this blog post, we will discuss the Linux file system, its different types, and the permissions associated with it. Become Expert in Linux with Linux Training
Linux File System
The Linux file system is a hierarchical structure of directories and files that is organized in a tree-like structure. The root directory (“/”) is at the top of the tree and contains all other directories and files. Each directory can have its own set of subdirectories and files, making the file system infinitely expandable.
Linux supports a variety of file systems, including ext2, ext3, ext4, XFS, Btrfs, and more. The most commonly used file system is ext4, which is the default file system in most Linux distributions.
Linux Permissions
Linux file permissions control access to files and directories on the system. There are three types of permissions: read, write, and execute. Each permission can be assigned to the owner of the file, the group that the owner belongs to, and others (everyone else).
The read permission allows the user to view the contents of a file or directory. The write permission allows the user to modify the contents of a file or directory. The execute permission allows the user to run a program or script.
The permissions can be viewed using the “ls -l” command in the terminal. The output of the command displays the permissions, the owner of the file, the group that the file belongs to, the size of the file, and the date and time the file was last modified.
Changing Permissions
Permissions can be changed using the “chmod” command in the terminal. The command can be used to add or remove permissions for the owner, group, and others. For example, to give the owner of the file read, write, and execute permissions, you would use the command “chmod u+rwx file.txt”.
Permissions are represented by a set of three digits. The first digit represents the owner’s permissions, the second digit represents the group’s permissions, and the third digit represents the permissions for others. The digits are calculated as follows:
- 4 = read permission
- 2 = write permission
- 1 = execute permission
For example, if a file has permissions 755, it means that the owner has read, write, and execute permissions, while the group and others have only read and execute permissions.
Changing File Permissions
You can change file permissions using the chmod command. The chmod command takes a linux file permission string as an argument, which is a combination of the letters u (for the owner), g (for the group), o (for others), and a (for all), followed by the permission type (r, w, or x), and a + or – sign to add or remove the permission. For example, to add write permission to a file for the owner, you can use the following command:
chmod u+w file.txt
Linux File System Security
File system security is critical in a Linux environment. Unauthorized access to files and directories can result in data loss, theft, or damage. Linux file system security is managed using user accounts, groups, and permissions.
Each user on the system has a unique user account with a unique username and password. User accounts are assigned to groups, and groups are assigned to files and directories. Permissions are assigned to users and groups, and the permissions control access to files and directories.
In addition to file permissions, Linux also supports access control lists (ACLs), which provide more granular control over file system security. ACLs allow you to assign permissions to specific users and groups, even if they are not the owner of the file or directory.
Conclusion
Understanding Linux file systems and permissions is essential to managing and securing your Linux environment. The Linux file system is organized in a hierarchical structure, and permissions control access to files and directories. Linux supports a variety of file systems, and the most commonly used file system is ext4. Linux file system security is managed using user accounts, groups, and permissions, and access control lists provide more granular control over file system security.
