CIS 191 – Lesson 2 System Administration

CIS 191 – Lesson 2 System Architecture Component Architecture –The OS provides the simple components from which you build complex applications. Client/Server Architecture –Applications are separated, usually across a network, into one component that listens for requests and provides a resource to a second component – the client Layered Architecture –Complex programs are created with layers of software each having well defined interfaces.

CIS 191 – Lesson 2 software Layers of a multi-user multi-tasking operating system users hardware operating system applications system commands libraries kernel system call interface resource management device drivers

CIS 191 – Lesson 2 Operating System Juggles users & programs across limited hardware resources Runs programs for multiple users Provides common services for programs and users Shares hardware resources between competing programs and users users programs hardware Basic role of a multi-user multi-tasking operating system

CIS 191 – Lesson 2 Architecture Dependent Kernel Code Kernel Space Process Management Memory Management Network Stack Virtual File System User Space Device Drivers Kernel 1 Hardware System Call Interface Users Commands & Utilities Shell X / Desktops (multi-user) GNU C Library (glibc) Programs (multi-tasking) Applications 1 See “Anatomy of the Linux kernel” by M. Tim Jones at GNU/Linux Operating System Architecture Richard Stallman started the GNU project in 1983 to create a free UNIX- like OS. He Founded the Free Software Foundation in In 1989 he wrote the first version of the GNU General Public License Linus Torvalds, as a student, initially conceived and assembled the Linux kernel in The kernel was later re- licensed under the GNU General Public License in 1992.

CIS 191 – Lesson 2 rootly powers

CIS 191 – Lesson 2 Root Account and Superuser “Superuser” privileges include installing software and modifying system configuration files. The administrator account is named root. root has all superuser privileges and is “all- powerfull”. Be very careful when logged on as root! Ways to obtain root privilege: login as root (need to know root password) login as regular user and use the su command (need to know root password) login as regular user and use the sudo command. (do not need to know root password, but need to preconfigure /etc/sudoers file.

CIS 191 – Lesson 2 Root Account and Superuser /etc/passwd Root account uid=0 gid=0 Home directory

CIS 191 – Lesson 2 For each top level directory, determine the following: 1.How many files are contained therein? find. | wc –l 2.How much disk space is being used? du –sh. 3.What is the predominant type of file in the directory? file * | more 4.cd../next The High Hurdles Exercise

CIS 191 – Lesson 2 Essential Tasks Software Installations and Upgrades Maintaining Hardware Performing Backups Managing User Accounts Monitoring the System Troubleshooting Helping Users Maintaining Local Documentation

CIS 191 – Lesson 2 Types of Installations CD, DVD, or ISO image Live CD/DVD Attended vs. Unattended Local vs. Network Imaging software (Ghost, ImageCast) Build from scratch

CIS 191 – Lesson 2 Three steps to an installation 1.Prepare the storage device Partition the disk Format the filesystems Select mount points for those filesystems 2.Copy the selected packages Package groups, packages, files 3.Write out the boot loader MBR or boot sector (GRUB, LILO, SYSLinux) Everything else is configuration