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