Virtual Signals

  Shell – Shell is a program that takes command from the keyboard and gives them to operating system to perform. We also called it as a command line interface (CLI). Terminal – Terminal a tool which you can used to pass a shell command. It’s lets you interact with shell. File System – File system in Linux arranged in a hierarchical directory structure like tree diagram. Root ( / ) is a main directory under which we have other directories. Below are the directories under root file system, Basic Commands - $ PWD – To check present working Directory. $ cd – Change directory $ ls – List the files or directories.  

  History of Linux – In 1964 Bell Laboratory stats a project in which they want to develop multiuser operating system. Dennis Ritchie and Ken Thompson was part of the project. Then in 1969 Bell Laboratory withdraw the project due to lack of results. But Dennis Ritchie and Ken Thomson started the project again from the beginning and developed a operating system called UNICS/UNIX (Uniplexed Information and computing services), and the source code of this operating system was freely available. Then in 1975 UNIX version 6 gain popularity and some companies started taking benefit of it and developed their own flavours of UNIX. IBM developed AIX, Sun system developed Sun Solaris, Apple developed MAC OS, HP developed UX. But all these operating system was not freely available, at that time Linus Torvalds was student and he wants to research on UNIX operating system and operating system was not freely available at that time so he started developing his own flavour of UNIX called ...

  What is operating system -  An operating system is the software that manages the computers hardware and provides a convenient and safe environment for running programs. It acts as an interface between programs and hardware resources that these programs access (like memory, hard disk and printer). It is loaded into memory when a computer is booted and remains active as long as the machine is up. Key Features of an operating system -  The operating system allocates memory for the program and loads the program in it. It also loads the CPU registers with control information related to the program. The registers maintain the memory locations where each segment of a program is stored. The instructions provided in the program are executed by CPU. The operating system keeps track of the instructions that was executed last. This enables it to resume a program if it had to be taken out of the CPU before it completed execution. If the program needs to access the hardware, it makes...