RCHE Red Hat Certified Engineer Linux Study Guide[c] Exam (Rh302)

Here are some of the key points from the certification objectives in Chapter 1.

Basic Linux Knowledge

• Linux is managed through a series of text configuration files.

• Even though Red Hat Enterprise Linux now has a rescue CD with text editors such as emacs, you need to know how to restore a system from a rescue floppy, which normally includes just the vi editor. Therefore, you need to know how to use vi.

Linux Filesystem Hierarchy and Structure

• Linux directories are organized to the Filesystem Hierarchy Standard (FHS).

• In the FHS, devices such as mice and hard drives are grouped in the /dev directory. Some /dev files have logical names such as mouse and modem and are linked to the actual device files.

• FHS partitions can be managed and formatted with the fdisk, fsck, and mkfs commands.

• The Logical Volume Manager allows you to consolidate multiple partitions in one filesystem, on one directory.

• Once configured, Linux directories can be mounted on a partition through /etc/fstab or directly with the mount command.

Basic Commands

• Linux administrators need to know how to use the command line interface.

• Basic commands allow you to navigate, find the files that you need, read file contents, create new files, and more.

• File filters allow you to search through the files themselves for specific citations or other file characteristics.

• Administrative commands allow you to manage Linux in a number of ways, including running processes and logged-in users.

Printing

• The default Red Hat Enterprise Linux print system is CUPS.

• You can configure printers by directly editing the files in the /etc/cups directory, or by running the Red Hat Printer Configuration tool, redhat-config-printer.

Shells

• Command lines are based on a shell.

• With the right permissions, you can set up shell programs in executable scripts.

• The way a shell works depends on the settings in its variables and parameters. Some variables and parameters are grouped in the inherited environment, which maintains settings from shell to shell.

• With stdin, stdout, and stderr, you can manage different data streams.

Basic Security

• Basic security within Linux is based on file permissions, users, groups, and umask.

• The SUID and SGID bits allow you to share owner-level permissions with different users and groups.

• Shadow passwords hide user authentication data. The Shadow Password Suite protects user and group passwords in files that should be accessible only to the root user.

System Administration

• While it's normally best to log in as a regular user, it's faster to log in as the root user for the RHCE and RHCT exams.

• Standard files for new users are kept in /etc/skel.

• Daemons are processes that run in the background.

• Network service can be controlled through scripts in the /etc/rc.d/init.d directory.

• The cron daemon helps you schedule different jobs, including backup and restore jobs, which should be done when network use is at a minimum.

• When you have problems, system log files, as organized by /etc/syslog.conf, provide important clues to the causes.

Basic TCP/IP Networking

• Most of the work in TCP/IP networking is with configuring IP addresses.

• There are three different sets of private IPv4 addresses suitable for setting up TCP/IP on a LAN.

• Tools such as ping, ifconfig, and netstat can help you diagnose problems on that LAN.

• Name resolution configuration files determine how your computer finds the right IP address.

Standard Network Services

• There are a number of standard network services. They include NFS, sendmail, POP, IMAP, FTP, DNS, DHCP, Samba, Apache, and NIS.

• Each of these services, when installed, can be configured to start and stop through the scripts located in the /etc/rc.d/init.d or /etc/xinetd.d directories.

Basic Network Security

• Basic network security settings can depend on allowing or denying access to different computers by their IP addresses or by the desired TCP/IP port.

• Computers behind a firewall can be protected through Network Address Translation or various iptables commands.

Basic Hardware Knowledge

• The focus of the RHCE exam is on computers built with an Intel-based architecture.

• An Intel-architecture PC has three basic communications channels: IRQ ports, I/O addresses, and DMA channels.

• The latest version of Red Hat Enterprise Linux as certified requires at least 256MB of RAM.

• You can set up Linux on IDE, SCSI, USB, or IEEE 1394 hard drives. However, the BIOS of a PC can load Linux boot files only from the first two IDE or SCSI hard drives or a boot floppy.

Hardware Compatibility

• Linux has come a long way the last few years, and you should have little problem installing it on most modern PCs.

• You may not be able to install Linux on every PC; there are occasional problems on newer laptop computers.

• The best places to look for compatible hardware are the Hardware HOWTO of the Linux Documentation Project or the Red Hat Hardware Compatibility List.

• Red Hat Enterprise Linux has a very capable plug and play service that can configure most current hardware.

• Closely related to plug and play are the ACPI and APM power management standards.

Configuring External Devices

• There are five basic categories of external devices: serial, parallel, USB, IEEE 1394, and PCMCIA.

• Serial port devices are usually linked to specific device files. For example, /dev/modem is often linked directly to a specific serial device file.

• Parallel port device configuration can be more complex. For example, a separate configuration utility is required to recognize devices such as printers.

• While Linux supports USB and IEEE 1394, support for many specific USB and IEEE 1394 devices is still in the works.

• Linux supports PCMCIA cards, also known as PC Cards, through the Card Services package, which includes drivers for the PCMCIA adapter and individual cards.

Preparing to Install Linux

• Installing on most Intel-based computers is pretty straightforward, but you can save yourself much time and frustration by knowing exactly what hardware you have.

• It can help to know the make and model number for each of the following components: hard drive controllers, network adapters, graphics cards, and sound adapters.

• If possible, also find the resolution and horizontal and vertical refresh rates of your monitor.