Introduction to Operating Systems Note Packet # 1 CSN 115 Operating Systems Genesee Community College CSN Lab Overview Dual booted Windows/Linux Workstations Linux workstations currently run CentOS and Ubuntu. Room on drives to install other operating systems Servers: external/internal server (csnlinux.genesee.edu) Runs CentOS 7 External internet address: (50.59.144.251) Internal internet address: 10.255.255.12 Runs a web server (apache) and a login server (SSH) Provides authentication to Fedora workstations (LDAP) Provides Home Directories (NFS)
Definitions Web Server - a program, service or machine that provides web pages to a client. Client - a program or machine that asks for, and ultimately receives, data from a server. Apache - one of the many programs that can serve up web pages SSH (Secure Shell) - a secure (encrypted) way to execute commands on a remote machine. LDAP (Lightweight Directory Access Protocol) - a service that provides similar functions to NIS. Allows a quick lookup of information about objects in a database. NFS (Network File System) - a service that provides shared storage to many clients on a network. External Server Hosts the website for the course. Access at https://csnlinux.genesee.edu Course web page is at http://csnlinux.genesee.edu/opsys The notes and documents are password protected: Username: linux Password: linux (note: this is different from your account username/password). You may also access your account from the outside using secure shell (ssh).
Internal csnlinux Server Holds all the username/password information for student accounts to all workstations in the lab: LDAP (Lightweight Directory Access Protocol) Holds student files, data, settings for all workstations in the lab: NFS (Network File System) Allows users to log into the csnlinux network from inside and outside the lab: SSH (Secure Shell) Understanding Operating Systems Software Collection of instructions that control the tasks a computer performs Can be changed without disassembling the computer and rewiring Operating system Software that helps other programs control computer hardware and interact with users Application Software program that provides service for computer user Cannot act without permission from operating system
Operating System Functions Initialize computer hardware Allocate system resources to programs Keep track of multiple programs running at same time Provide organized method for all programs to use system devices The most common type of operating system today: Multiuser, Multiprocess. Other types include: single user, multiprocess and single user, single process. Operating System Functions Major operating system components: Kernel * Device drivers Shell Utility programs and Library Files Graphical user interface (GUI) * the kernel is the "core" of the operating system. The Linux Kernel is currently at version 3.16.1. Each update to the kernel provides support for new hardware and subsystems.
Operating Systems: Top -Down A look at the different "layers" in most modern operating systems. You are at the top. Users Application User Interface Libraries, System Call Interface (API), System Utilities Operating System Kernel and Drivers Computer Hardware A Few Operating Systems Microsoft Windows XP, Vista, 7, 8, 10, Server 2008, Server 2012, Server 2016 Unix (many companies including IBM, HP) Linux (many companies including RedHat, Canonical, Google) Android (based on Linux) Mac OS and ios (Apple) Blackberry OS, DOS, Cisco IOS,... many others!
What is Linux? A fully-networked 32/64-Bit Unix-like Operating System Multi-user, Multitasking, Multiprocessor Has the X Windows GUI with GNOME, KDE and many other desktop environments Coexists with other Operating Systems Runs on multiple platforms Includes the Source Code: Open Source Birth of Linux In 1991, Linus Torvalds, a 21 year old student at University of Helsinki, Finland, posted this message to a newsgroup: "I'm doing a (free) operating system (just a hobby, won't be big and professional) for 386/486 clones." Today an estimated 65-100 million users 1% to 2% using Linux desktops 20%-40% Linux servers (facebook, youtube, google,...) Many, many more if you count mobile devices that run linux.
Linux Companies: Red Hat Fedora distribution Free product Currently at Fedora 28 Based on Red Hat Linux Red Hat Enterprise Linux configurations Currently at Red Hat Enterprise Linux 7 Sold as a subscription including tech support Uses Fedora as its "development" distribution CentOS is free clone of Red Hat, uses Red Hat code base Other Linux Companies/Distros opensuse Debian Ubuntu (based on Debian code) Mint (based on Ubuntu) Mageia (based on Mandriva) Arch PCLinuxOS Slackware CentOS (based on Red Hat Enterprise) Google (Chrome OS, Android OS)
What is Open Source? Shared software, source code is freely available for download on the web. Different definitions: GNU GPL (General Public License) BSD license Mozilla Public License Many, many others! Read article "A Short Guide to Open Source Licenses" on web. Open Source Projects: XFree86, MySQL, Perl, PHP, Python, Apache, OpenOffice, Mozilla, many others. Linux Certification Industry certification programs Red Hat Certified System Administrator (RHCSA) Red Hat Certified Engineer (RHCE) LPI Certification Linux Certified Administrator (LCA) Certification Linux+ Certification Novell Certified Linux Administrator
Careers in Linux and other OS's Systems administrator Network administrator Software engineer, computer programmer Trainer Technical writer Cyber Security Business consultant Product development (especially mobile devices) Web Development Embedded Devices Role Roles of a Sys Admin Make technology work and continue to work for those who do real work of organization Enable others to use technology benefits Responsibilities Create new user accounts Maintain system hardware Back up Data and Programs Train end users Keep system(s) running smoothly Documentation; define procedures and policies Recover from emergencies Plan deployment