This module covers Introduction to Linux, History of Linux, Features of Linux, Advantage of Linux, File System Hierarchy Standard, Knowing root, Linux Commands, Working with Files and Directories, etc.
Portability is the software codebase feature to be able to reuse the existing code instead of creating new code when moving software from an environment to another.
In computing, 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 kernel's responsibilities include managing the system's resources (the communication between hardware and software components).
Any file to which data is spooled to await the next stage of processing. A device file or special file is an interfacefor a device driver. Device files often provide simple interfaces to peripheral devices, such as printers. But they can also be used to access specific resources on those devices, such as disk partitions.
A terminal consists of a screen and keyboard that one uses to communicatewith a computer.
I Am Linux-Introductory Module on Linux
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Linux an open source operating system. Its source code canbe used freely, freely modified, and redistributed, bothcommercially and non-commercially, by anyone underlicenses such as the GNU General Public License
The Unix operating system was conceived and implementedby Ken Thompson and Dennis Ritchie (both of AT&T BellLaboratories) in 1969 and first released in 1970. Itsavailability and portability caused it to be widelyadopted, copied and modified by academic institutions andbusinesses. But it was not freely distributed.
In 1983, Richard Stallman started the GNU project. His ideawas that unlike other products, software should be free fromrestrictions against copying or modification in order to makebetter and efficient computer programs. With his famous1983 manifesto that declared the beginnings of the GNUproject
MINIX, a Unix-like system intended for academic use, wasreleased by Andrew S. Tanenbaum in 1987. MINIX was freeand designed for education in computer science. Students ofComputer Science all over the world read the codes tounderstand the very system that runs their computer.
In 1991 while attending the University ofHelsinki, Torvalds, curious about the operating systems andfrustrated by the licensing of MINIX limiting it to educationaluse only (which prevented any commercial use), began towork on his own operating system which eventually becamethe Linux kernel. In order to make the Linux available forcommercial use, Torvalds initiated a switch from his originallicense (which prohibited commercial redistribution) to theGNU GPL.
Here are some basic and major features of Linux. Free and Open source code for all: All source code of Linux is available, including the whole kernel and all drivers, the development tools and all user programs; also, all of it is freely distributable. Plenty of commercial programs are being provided for Linux without source, but everything that has been free, including the entire base operating system, is still free. c Multiuser: Several users can logon to the same machine at the same time There is no need to have separate user licenses. Multitask: Several programs can run at the same time. Multiplatform: runs on many different CPUs, not just Intel. Networking: Linux supports networking and many network protocols like TCP, IPv4, IPv6, etc.
Forget about virusesLinux hardly has any viruses. A Linux virus is not impossible to get.However, Linux makes it very hard for this to happen, for several reasons: Most people use Microsoft Windows, and pirates want to do as much damage (or control) as possible: therefore, they target Windows. More eyes make fewer security flaws. Linux is Open source software, which means that any programmer in the world can have a look at the code (the "recipe" of any program), and help out, or just tell other developers
Is your system unstable?Have you ever lost your precious work because Windows crashed? Do youalways shut down your computer the proper way, or do you sometimes justswitch it off because Windows has gone crazy and doesnt let you do anythinganymore? Have you ever gotten the "blue screen of death" or error messagestelling you that the computer needs to be shut down for obscure reasons?When a system crashes, it needs to be shut down or restarted. Therefore, ifyour computer can stay up and running for a long time, no matter how muchyou use it, then you can say the system is stable. Well, Linux can run for yearswithout needing to be restarted (most internet servers run Linux, and theyusually never restart). Of course, with heavy updates, it still needs to berestarted (the proper way). But if you install Linux, and then use your systemas much as you want, leaving your computer on all the time, you can go onlike that for years without having any trouble.
Dont pay for your operating systemUnless you obtained Windows illegally, you probably paid for it. Linuxcompletely free of charge. Of course, some companies are making goodbusiness by selling support, documentation, hotline, etc., for their own versionof Linux, and this is certainly a good thing. But most of the time, you wontneed to pay a cent.
Need new software? Dont bother searching theweb, Linux gets it for you.If you want to check out a new piece of software in Windows, youll need to: Search the web to find which piece of software suits your needs. Find a web site that allows you to download it. Maybe pay for it. Actually download the software. Install it. Sometimes reboot your computer.Thats a lot of work to just try out something new.With Linux, everything is much simpler. Linux has what is called a "packagemanager": each piece of software is contained in its own "package". If youneed some new software, just open the package manager, choose thepackage and install it.
Forget about driversImagine you want to install Windows on a whole new, untouched, computer.For each little piece of hardware youll have to find the latest driver (or use aCD), install it, and reboot from time to time. Video card, soundcard, keyboard, mouse, motherboard chipset, etc. (better do the video carddriver first or youre stuck with your high-end screen showing a very lowresolution mode). And that comes after an already rather long installation ofWindows itself. Linux doesnt need separate drivers. All the drivers are already included in the Linux kernel, the core of the system, and that comes with every single Linux installation. This means: A very fast and standalone installation process. Once youre done, you have everything you need to start working (including the software youll be using,. Out-of-the-box ready peripherals.
The Filesystem Hierarchy Standard (FHS) defines the main directories andtheir contents in Linux operating systems. / Primary hierarchy root and root directory of the entire file system hierarchy. /boot Contains the boot loader. It contains everything required for the boot process /etc Contains all the configuration files like DNS, Proxy, Apache and other programs. /home Contains the home directory of a normal user. /root Contains the home directory of the super user, i.e., root. /bin Contains commands that may be used by both the system administrator and by users. /sbin Utilities used for system administration (root-only commands) are stored in /sbin, /usr/sbin, and /usr/local/sbin. /sbin contains binaries essential for booting, restoring, recovering, and/or repairing the system in addition to the binaries in /bin.
/lib The /lib directory contains those shared library images neededto boot the system and run the commands in the root filesystem, ie. bybinaries in /bin and /sbin./usr Secondary hierarchy for read-only user data; contains themajority of multi-user utilities and applications./mnt or /media In Linux, all the removable devices like cdrom, pendrive, external hard disk, etc, are mounted /mnt or /media directory.Both are temporary mounting point and their work are same./var contains variable data files. This includes spool directories andfiles, administrative and logging data, and transient and temporaryfiles./dev Directory is the location of device files./tmp Temporary files./opt This directory is reserved for all the software and add-onpackages that are not part of the default installation.
Linux has two interfaces: 1. Command Line Interface (CLI) 2.Graphical User Interface (GUI)It has 7 virtual consoles, by pressing Alt+Ctrl+f1 toAlt+Ctrl+f7, we can switch from one console to another.Alt+Ctrl+f1 – 1st consoleAlt+Ctrl+f2 – 2nd consoleAlt+Ctrl+f3 – 3rd consoleAlt+Ctrl+f4 – 4th consoleAlt+Ctrl+f5 – 5th consoleAlt+Ctrl+f6 – 6th consoleAlt+Ctrl+f7 – 7th console
Root is by default an administrator name in Linux.After login, when you open a terminal. You see the following prompt.Here, root is admin name, localhost is the system name, tild(~) indicates thehome directory (this implies, root is in his home directory) and # indicatesauthorized use, that means, root has the authority to access the particulardirectory. Incase of a normal user, it will show $ prompt.
whoami - print effective userid.date - print or set the system date and time.cal - displays a calendar.pwd - print name of current/working directory.ls –l - list directory contents with details.cd - Change the working directoryclear - Clear the screenGetting help:-whatis (command) - searches a set of database files containing short descriptions of system commands for keywords and displays the result on the standard output.which (command) - Displays where a particular program in your path is located.man (command) - manual pages from the Linux Documentation Project.info (command) - read Info documents.command --help - for more help.
Creating a fileCopying a fileMoving a fileRemoving a file(To remove a file forcefully, add –f between command and file, then itwont ask you for the confirmation)
Renaming a fileIn Linux everything is file. You should know how to edit a file.Later in the module you will understand how to edit a fileusing gedit and vi editor.
Creating a directoryCreating sub-directoriesCreating multiple directoriesCopying a directory(To remove a directory forcefully, add –f between command anddirectory, then it wont ask you for the confirmation)
Moving a directoryRemoving a directoryTo remove an empty directory, type commandRenaming a directory(To remove a directory forcefully, add –f between command anddirectory, then it wont ask you for the confirmation)
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