Question-1 Explain the role or function of the kernel.
- Each process asks for the system resources like computing power, memory network connectivity etc. The kernel is the bulk of the executable code in charge of handling such request.
- The kernel is the main component of most computer operating systems. It is a bridge between applications and the actual data processing done at the hardware level.
The following are the major role of the kernel
- The kernel’s primary function is to manage the computer’s resources and allow other programs to run and use these resources. These resources are- CPU, Memory and I/O devices.
- The kernel is in charge of creating, destroying and handling the input output of the process.
- Communications amongst the different processes is the responsibility of the kernel.
- The memory is the major resource of the computer and the policy used to deal with it is a critical.
- The kernel builds a virtual address space for all the process on the top of the resource. The different parts of the kernel interact with the memory management subsystem by using the function calls.
- The kernel builds the structured file system on the top of the unstructured hardware.
- Kernel also supports the multiple file system types that is different way of managing the data.
- Every system maps into the physical device.
- All the device control operations are performed by the code that is specific to the device being addressed. This code is called device driver.
- It will be managed by the operating system and also control the program execution according to the network activity.
- Routing and address resolution issues are also handled by the kernel.
Inter – Process Communication
- Kernel provides methods for Synchronization and Communication between processes called Inter- Process Communication (IPC).
- There are various approaches of IPC say, semaphore, shared memory, message queue, pipe (or named fifo), etc.
Security or Protection Management
- Kernel also provides protection from faults (error control) and from malicious behaviors (Security).
- One approach toward this can be Language based protection system, in which the kernel will only allow code to execute which has been produced by a trusted language compiler
Question-2 Explain in brief roles/ functions of shell.
UNIX shell act as a command interpreter.
- It gathers input from user and executes programs based on that input, when a program finishes executing; it displays that program’s output.
- It is primary interface between a user sitting at his terminal and operating system,unless the user is not using a graphical interface.
- A shell is an environment in which user can run our commands, programs, and shell scripts.
- There can various kinds of shells such as sh (bourne shell), csh (C shell), ksh (korn shell) and bash.
- When any user logs in, a shell is started.
- The shell has the terminal as standard input and standard output.
- It starts out by typing the prompt, a character such as $, which tells user that shell is waiting to accept command.
- For example if user types date command,
- $ date
- Tue Feb 26 06:01:19 IST 2019
- The shell creates a child process and runs date program as child.
- While the child process is running, the shell waits for it to terminate.
- When child finishes, the shell types the prompt again and tries to read the next input line.
- Shell is work as interface, command interpreter and programming language.
- Shell – As interface
- Shell is interface between user and computer.
- User can directly interact with shell.
- Shell provide command prompt to user to execute commands.
- Shell – As command interpreter
- It read command enter by user on prompt.
- It Interpret the command, so kernel can understand it easily.
- Shell – As programming language
- Shell is also work as programming language.
- It provides all features of programming language like variables, control structures and loop structures.