Kernel is the core part of Unix Operating System, Unix has Kernel based architecture, A Kernel is responsible for the communication with the hardware. A Kernel provides various kinds of services for the Operating System. The services offered by the kernel is implemented using various methods/routines, etc.
When the system is booted The kernel is loaded into the main memory first. The kernel manages the memory, files and peripherals devices. The Kernel also maintains the date and time, launches applications and allocates system-resources.
Functions of Kernel
- Memory Management- The kernel is responsible for allocation and deallocation of memory etc.
- Scheduling of process so that system can work efficiently.
- Coordination and data transfer operation between the input/Output devices and memory.
- The Kernel is also responsible for taking the instruction/command from the shell and execution of the command and displaying of result on the terminal.
- The Kernel also enforces various security measures to prevent unauthorized access to the system.
User Levels in Unix
In Unix Operating system there are different category of User/ user levels. This categorization helps to implement the security to the information. The users are given the permission according to the requirement.
Different types of Users/ User levels in Unix
User/owner – u
The owner has full control over the information/files created. Only the super user can change the owner permission.
Group – g
Group is the collection of users according to the similarities, interest, requirements etc.
Others – o
All Other users on the network who are not the part of your group/network are treated as others.