Inside that system box is the system’s brain: the microprocessor (Intel Pentium 4, for example), also called the CPU, which performs the instructions contained in a computer program. When the microprocessor runs a computer program, that program’s instructions are stored in the memory, or RAM (random-access memory). RAM means that any part of the memory can be accessed randomly, in any order.
The system box has another crucial component: the hard drive (or hard disk, as it’s sometimes called). The hard drive is the permanent storage space for computer programs and data; it’s permanent in the sense that the contents don’t disappear when you power off the PC. The hard drive is organized into files, which are in turn organized in a hierarchical fashion into directories and subdirectories (somewhat like papers organized in folders inside the drawers of a file cabinet).
To keep a Linux system running properly, you (or someone else) must make sure that the hardware is working properly and that the files are backed up regularly. There’s also the matter of security, making sure that only legitimate people can access and use the system. These tasks are called system administration.
If you use Linux at a big facility with many computers, a full-time system administrator probably takes care of all system-administration tasks. On the other hand, if you run Linux on a home PC, you are the system administrator. Don’t let the thought frighten you. You don’t have to know any magic incantations or prepare cryptic configuration files to be a system administrator. Most Linux distributions include many graphical tools that make system administration a point-and-click job, just like running any other application.
Distribution media for Linux systems
Some Linux distributions come on a single DVD-ROM or require you to create it from files downloaded from a site. After installation, the Linux kernel and all the applications are stored on your hard drive, which is where your PC looks first when you tell it to do something.Typically, the hard drive is prepared to use Linux during the installation process. After that, you usually leave the hard drive alone except to back up the data stored there or (occasionally) to install and update applications.
Using USB drives or DVD-ROMs in Linux is easy. While you’re logged in at the GNOME or KDE desktop, just pop a DVD into the drive or a thumb drive into the USB port, and the system should automatically detect the media. Depending on the Linux distribution, a DVD/CD-ROM icon appears on the desktop, or a file manager opens and displays the contents of the DVD/CD-ROM. If all else fails, you can type a simple mount command to associate the media with a directory on your system. The process of accessing the files on a device from Linux is called mounting the CD or the DVD.
Peripheral devices for Linux systems
Anything connected to your PC is a peripheral device, as are some components (such as sound cards) that are installed inside the system box. You can configure and manage these peripheral devices in Linux.One common peripheral is a printer, typically hooked up to the USB (Universal Serial Bus) or parallel port of your PC. (Many distributions come with a graphical printer configuration tool that you can use to configure the printer.)
Another peripheral device that needs configuration is the sound card. Most Linux distributions detect and configure sound cards, just as Windows does. If Linux can’t detect the sound card correctly, you may have to run a text mode or graphical tool to configure the sound card.
Linux configures other peripheral devices, such as the mouse and keyboard, at the time of installation. You can pretty much leave them alone after installation.
Nowadays, PCs come with the USB interface; many devices, including printers and scanners, plug into a PC’s USB port.
One nice feature of USB devices is that you can plug them into the USB port and unplug them at any time; the device doesn’t have to be connected when you power up the system. These devices are called hot-plug because you can plug in a device when the system is hot, meaning while it’s running. Linux supports many hot-plug USB devices. When you plug a device into the USB port, Linux loads the correct driver and makes the device available to applications.
File systems and sharing for Linux systems
The entire organization of directories and files is the file system. You can manage the file system by using Linux. When you browse the files from the GNOME or KDE graphical desktop, you work with the familiar folder icons.A key task in caring for a file system is backing up important files. In Linux, you can use the tar program to archive one or more directories on a USB drive or on other media. You can even back up files on a tape (if you have a tape drive). If you have a CD or DVD burner, you can also burn a CD or DVD with the files you want to back up or save for posterity.
Linux can share parts of the file system with other systems on a network. You can use the Network File System (NFS) to share files across the network, for example. To a user on the system, the remote system’s files appear to be in a directory on the local system.Linux also comes with the Samba package, which supports file sharing with Microsoft Windows systems. Samba makes a Linux system work just like a Windows file or print server. You can also access shared folders on other Windows systems on your network.
Networks for Linux systems
Now that most PCs are linked in a local-area network (LAN) or connected to the Internet, you need to manage your connection to the network as well. Linux comes with a network configuration tool to set up the LAN. For connecting to the Internet with a modem, there’s usually a GUI Internet dial-up tool.If, like many users, you connect to the Internet with a DSL or cable modem, you need a PC with an Ethernet card that connects to the cable or DSL modem. You also have to set up a LAN and configure the Ethernet card. Fortunately, these steps typically are part of Linux installation. If you want to do the configurations later, you can by using a GUI network configuration tool.
Linux also includes tools for configuring a firewall, which is a protective buffer that helps keep your system relatively secure from anyone trying to snoop over your Internet connection. You can configure the firewall by using iptables commands or by running a GUI firewall-configuration tool.