The Linux operating system is a free and open source computer program that allows users to access multiple devices via the internet. In order to use the system, you'll need to install certain software components before being able to access files on your computer. One of these components is often referred to as "Linux". This is because it provides an interface between users and individual applications within their operating systems (for example, when using Windows).
User Privilege in Systems
File permissions are used in conjunction with other security measures like firewalls and antivirus software to prevent unauthorized access to sensitive data within your computer's files. File permissions allow users and groups of users who have been granted "sudo" privileges on their local machine (Linux) or network share (Windows) access only certain parts of that shared resource; for example, if you wanted everyone who has been given sudo rights on your home directory but not root rights on any other directories then you would need to assign them proper file permissions so they could write/delete anything inside those directories without affecting its integrity or security further down chain!
Permission Levels in Systems
There are three default permission levels: read, write and execute (or rwxr-xr-x). The first letter of each word stands for its meaning:
- Read[r] - You can read the contents of this file.
- Write[w] - You can change or delete this file.
- Execute[x] - This is the permission level that allows programs to run within your computer’s operating system.
In Ubuntu there are three types of users: User (the owner of the file), Group (the security group you are in), and Other (for the world to see). The actual permissions are represented as numbers, with each number corresponding to a specific permission level. For example, 0 corresponds to no permission at all while 7 corresponds to full access.
Below is a list of the common Linux file permissions and their corresponding levels:
When You are unable to change Permissions
If a user has write permission but not execute permission, they will only be able to modify files in directories they have write permissions for. They won't be able to run programs from those directories without additional privileges granted by another user who has superuser access on the system.
If you have both read and execute permissions, then you can run programs from any directory on your system without having to know what it contains or where it's located. However if you only have read access then all files within that directory are visible but they cannot be modified or run by anyone other than yourself (unless granted superuser status).
Understanding Ubuntu permissions system
As I said earlier, Ubuntu has three types of users : owner, groups and others. The Permissions in the System We can view by listing command and -l attributes.
ls -lThe three default permissions are: read, write and execute. This means that you can view files and folders, but not modify them. If you want to modify a file or folder, then you need to use the chmod command with 7 as the mode (i.e., 755). For example:
chmod 755 /home/user/directoryIn This Example we can see that The Owner of document/ Directory has Read, Write and Execute access. and the group and others have Read and Execute Access Only.
To Learn More about chmod visit : Everything About Chmod