Linux Permissions Explained

Technical writer

Linux Linux-System Sistema Linux O sistema Linux

27.01.2025

Reading time: 6 min

In Linux, permissions are extremely valuable in dealing with access to folders as well as files. It makes sure proper authority over which one can deal with them. Effectively handling these privileges is fundamental for enhancing system file management and security. These privileges give groups or users the ability for reading, executing, or modifying, directories and their content. These rules safeguard data and restrict access, particularly in environments with more than one user. Each folder or file comes with particular rights that represent what users can accomplish.

This article will demonstrate the basis of permissions, point out access, understanding, and changing privileges for them, and manage folders and their content.

Basis of Permissions

For beginners, the directories or file privileges can be challenging. It involves the concepts of types and groups as below:

Types

In Linux, each folder or file holds three kinds of permissions, each serving a particular purpose:

Read (r): It indicates the permission to view the file’s content or enlist the items inside the folder.
Write (w): It allows modifications to the particular file or addition and deletion of files inside the directory.
Execute (x): It permits the file execution as the program or getting the folder content.

Groups

They are classified into three groups, each serving a particular role:

User (Owner): It indicates the user who has the ownership rights of the folder or file.
Group: It indicates a bunch of users having shared access rights.
Others: It includes those who are not owners or participants of the desired group.

Permission Formats

Privileges are visualized in two formats: symbolic and octal. The symbolic employs symbols to mean rights, r indicates reading, w refers to writing, and x is utilized for the execution purpose. In contrast, the octal utilizes numbers, where 4 means reading, 2 stands for writing, and 1 signifies execution.

Linux Display Permissions

Linux offers several methods to examine privileges. Individuals can employ a terminal for detailed information or go through the file manager's properties option for a graphical visualization.

Using GUI

This approach is the most straightforward for evaluating rights of permissions. It permits individuals to display them through the file manager's properties.

To employ this method, hit the right-click on the desired folder and click Properties:

Next, navigate to Permissions for viewing the permissions given to the particular directory and its content:

In the figure, readers can see and adjust privileges for directories and their content, defining what the group is permitted to do, such as modifying, accessing, or deleting them. Additionally, it provides security context info and offers the choice to implement these privileges to all enclosed files:

Through the ls Command

You can employ the ls command along with -l, followed by the specified folder or file, to analyze its stats, including privileges:

ls -l <file_or_directory_name>

It retrieves thorough entries, including file privileges and a variety of properties. For instance, the below one retrieves the privilege attributes of the Downloads:

ls -l Downloads

In the output, the starting part indicates the permissions for all files or folders. For instance, -rw-rw-r-- describes the file as having reading and writing rights for the group as well as the owner. Also, reading-only privileges for others. drwxrwxr-x demonstrates the particular folder possessing the privileges of reading, writing, and executing for the group and owner. Also, reading and executing privileges for others.

The next section describes the number of hard links to a particular file or folder. The next section shows (e.g., linuxuser) the owner. The next part shows the group which is corresponding with the directory or file. The fifth part describes the file's size in bytes.

Next you see the most recent modification date and time, and finally the seventh section shows the file or folder’s name.

Through the namei Utility

In Linux, namei is an effective utility that shows the individual sections of a file or folder path along with their rights:

namei -l /path/to/file

Now, employ the namei -l to visualize comprehensive details about the Downloads folder:

namei -l Downloads

In this outcome, f: Downloads relates to the last entry in the folder, e.g. Downloads. The d signifies that it is a directory. The rwxr-xr-x means that the linuxuser has the right to read, write, and execute. However, both the linuxuser owner and the group have the capacity to read and execute privileges. It confirms that the linuxuser group as well as a user have the owners' rights of the particular folder.

Through the stat Command

This utility retrieves comprehensive info about the particular folder and its content, e.g. files:

stat fileName

Let’s employ it to retrieve the comprehensive statistics of the Downloads:

stat Downloads

It retrieves the size of the file, rights, and a lot more:

Modifying Permissions

Editing file and folder rights are effective for system privacy purposes. Linux provides two main methods to revise privileges: symbolic and absolute mode.

Symbolic Mode

In this mode, individuals adjust permissions by adding (+), deleting (-), or setting (=) specific rights for the owner, group, or others. For making these modifications, the chmod is utilized.

Let's check out the permissions for the hostmanData file:

ls -l hostmanData

For adding execution access for the file’s owner, utilize the chmod utility as below:

chmod u+x hostmanData

Next, verify the updated privileges by running:

ls -l hostmanData

Absolute Mode

In this method, rights are given through octal synonyms. There, every digit is related to reading, writing, and executing access for the user, group, and others. For instance, the code line allows full privileges to the owner and gives reading and executing access to the group and others:

chmod 755 hostmanData

Modifying Owner Rights

The chown utility permits individuals to alter the folder's ownership and content. It allocates the new group or owner to maintain access control.

Modifying Ownership

We can alter the owner status of a particular directory or file via the chown. For instance, to alter the privileges of the hostmanData file to anees, employ the below code line:

sudo chown anees hostmanData

Next, confirm the changes via the following code line:

ls -l hostmanData

Modifying Group Ownership

For updating the owner of a group of files, you can employ the below syntax:

sudo chown :users hostmanData

The above line updates the group of the hostmanData from linuxuser to users:

Other Permissions

Linux permits individuals the appropriate way to handle advanced or complex operations via the below utilities:

setuid: It allowed the file to execute with the authority of the owner compared to the user when implemented to the particular executable file.
setgid: It permits the specific file for execution with the particular authority of the group that corresponds with the given file.
Sticky Bit: It makes sure that the file’s owner has the capacity for renaming or deleting particular files inside a particular folder.

Final Words

In Linux, permissions are significantly important for handling access to particular folders or files. It plays an essential impact in system management or security. In this article, we covered the basis of permissions, their authority and modification, and editing ownership. We also demonstrated special rights to deal with complicated tasks. With a solid comprehension of these concepts, users can effectively secure Linux and manage access with ease.