Introduction to Operating Systems

1. Introduction to Operating Systems Lesson 15 Red Hat Linux 8.0

2. Objectives • Describe how to install Linux. • Describe the Linux boot process. • Determine the hardware configuration of a Linux system. • Perform basic disk management operations. • Perform basic user management operations. • Perform proactive and reactive troubleshooting procedures. Lesson 15 – Red Hat Linux 8.0

3. The operating system is distributed over the Internet at no charge. The source code is also available to anyone at no charge. This lesson focuses on version 8.0 as developed and distributed by Red Hat. Linux Is User-Supported Lesson 15 – Red Hat Linux 8.0

4. “lilo” is the Linux loader program. lilo loads from the Master Boot Record on the hard drive. lilo can be edited to alter the way that Linux boots. The Boot Process Sample /etc/lilo.conf boot=/dev/hda map=/boot/map install=/boot/boot.b prompt timeout=50 message=/boot/message linear default=linux image=/boot/vmlinuz-2.4.2-2 label=linux read-only root=/dev/hda5 other=/dev/hda1 optional label=dos Lesson 15 – Red Hat Linux 8.0

5. Processes are constantly being started and terminated. Use the ps command to view currently executing processes. Linux Runs Multiple “Tasks” or Processes Lesson 15 – Red Hat Linux 8.0

6. Swap Space Is Virtual RAM • Linux moves processes between RAM and swap space. • An entire file system is dedicated to nothing but swap space. • The /proc directory holds information describing the configuration and current state of the swap space. Lesson 15 – Red Hat Linux 8.0

7. The Linux Directory is generally consistent over different versions of Linux. Most directories are only available to the root user. The Linux Directory /bin /etc /boot /dev  /lib /home /mnt /opt /sbin /tmp /usr /var Lesson 15 – Red Hat Linux 8.0

8. Linux File Systems Must Be Kept Healthy • Never turn off a Linux computer without first shutting down the operating system. • Use fsck to repair file systems. • Use if a file system does become corrupted • Performed automatically at boot time on most Linux installations • Never interrupt fsck! Lesson 15 – Red Hat Linux 8.0

9. User Permission Permissions applied to the owner of the file or directory Group Permission Permissions applied to users who belong to the same group to which the file is assigned Other Permission Permissions applied to users who do not fall into the above categories Permissions for Files and Directories Lesson 15 – Red Hat Linux 8.0

10. Settings for Permissions • Each set of permissions includes three specific yes/no settings: • Read • Write • Execute Lesson 15 – Red Hat Linux 8.0

11. Use Red Hat User Manager • Create accounts for people who will use the computer. • Do not give out the root user password. Lesson 15 – Red Hat Linux 8.0

12. Be a Proactive System Administrator • Keep a logbook of the changes you make to your computer. • Schedule and perform timely backups. • Keep an eye on the free space in your file systems. Remove temporary files and unneeded files. • Protect the root account. Lesson 15 – Red Hat Linux 8.0

13. Summary • The Linux boot process is configurable at almost any point in the process. • Many programs that execute at boot-time are written in the Bourne Shell Script programming language • Linux provides utilities and programs to monitor system resources and hardware configuration. • Disk drives are divided into partitions at the BIOS level and then into file systems at the Linux level. • Linux users, except the root user, are limited by file permissions and directory permissions. Lesson 15 – Red Hat Linux 8.0