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Linux interview questions

What is Kernel? Explain the task it performs. 

Kernel is used in UNIX like systems and is considered to be the heart of the operating system. It is responsible for communication between hardware and software components. It is primarily used for managing the systems resources as well.

Kernel Activities:

The Kernel task manager allows tasks to run concurrently.

Managing the computer resources: Kernel allows the other programs to run and use the resources

Resources include i/o devices, CPU, memory.

Kernel is responsible for Process management. It allows multiple processes to run simultaneously allowing user to multitask.

Kernel has an access to the systems memory and allows the processes to access the memory when required.

Processes may also need to access the devices attached to the system. Kernel assists the processes in doing so.

For the processes to access and make use of these services, system calls are used.

What is Linux Shell? What is Shell Script?

Linux shell is a user interface used for executing the commands. Shell is a program the user uses for executing the commands. In UNIX, any program can be the users shell. Shell categories in Linux are:

Bourne shell compatible, C shell compatible, nontraditional, and historical

A shell script, as the name suggests, is a script written for the shell. Script here means a programming language used to control the application. The shell script allows different commands entered in the shell to be executed. Shell script is easy to debug, quicker as compared to writing big programs. However the execution speed is slow because it launches a new process for every shell command executed. Examples of commands are cp, cn, cd.

What are Pipes? Explain uses of pipes.

A pipe is a chain of processes so that output of one process (stdout) is fed an input (stdin) to another. UNIX shell has a special syntax for creation of pipelines. The commands are written in sequence separated by |....