| Bash, the Bourne Again Shell, will be very familiar to Linux users. As a command line in-terpreter, it incorporates aspects of both the Korn (ksh) and C (csh) shells. A shell interprets and executes user commands. Bash is only one of many, evolving command line interpreters available for Unix. A computer’s Built-In Operating System, or Basic Input/Output System. The BIOS is used to set hardware oriented parameters on a computer, such as drive operation, clock settings, and screen drawing. The most common measure of computer storage. A byte is made up of eight binary digits, “bits,” and holds the equivalent of a single character, e.g., an “A,” “-,” or “.” So, one kilobyte holds 1000 bytes, or characters of information; one megabyte holds one million bytes; one gigabyte equals one billion bytes. A command-line login screen. Most Unix systems offer several consoles for multiple log-ins on one terminal, called virtual consoles. These consoles may be accessed by pressing ALT and the F1 through F11 keys. The Central Processing Unit, or a single integrated circuit that does the actual processing in a computer. Often, the box that encloses the whole computer unit is called a CPU. Not to be confused with a “hacker,” crackers attempt to break into systems for malicious purposes. Crackers use system resources to lock out legal users and break into other systems. Tight system security helps to deter crackers. A system in Unix that allows user to schedule the execution of programs automatically at specified intervals and times. A user’s files of cron jobs. Programs that run underneath the console application, or background processes. That is, daemons are programs that are often spawned by other programs to fulfill various tasks. Daemons run when they are needed, but turn themselves off when they are no longer necessary. Used as a standard replacement for IP addresses on the Internet: www.redhat.com is much easier to remember than 123.234.267.67. A domain name consists of at least two parts separated by “dots” (.): a top-level domain and a subdomain. The former are the established ends of all names: .com, .net, .org, .gov, and .mil. The subdomain is made up of a host name (www) and the subdomain (redhat). Together, they represent the fully-qualified domain name. A firewall filters incoming and outgoing packets of information on a network, allowing only authorized ones access. Simple firewalls built from ipchains can greatly enhance network security. File Transfer Protocol is usually used when up- or downloading files to and from a re-mote host. FTP can be used by registered users, or through an anonymous service, de-pending on a computer’s FTP configuration. Anonymous FTP service is often an insecure feature on servers, so should be avoid unless there is a great need for it. See Domain Name. One billion bytes of information. Graphical User Interface. Rather than a console session, most users prefer a GUI that al-lows for point-and-click interface to control the computer. The most basic part of the operating system, the kernel manages system resources like RAM, the processor, and other hardware devices. The kernel also provides other services used by other parts of the system. The Linux Loader, a boot management program, specifies the parameters of how Linux is to boot on a machine. LILO defines the partitions on which Linux and other operating systems exist, and it can be set up to password protect a Linux system and allow it to boot other operating systems as well. One million bytes. See Domain Name. Provides the service of linking IP addresses with domain names. Network File System allows access to shared volumes, directories, and files. Seven different ways that a Linux computer can boot. I.e., each runlevel turns on or off various services depending on what a user needs. For example, in single-user mode, not other users may login and a minimum of system resources are started; this mode is usually for diagnosing and fixing problems. A simple program of shell commands that can be executed with one command. A simple text file that is given the ability to be “run” like a program. See Bash. See Runlevel. Video Graphics Array is the standard for PC video display. The aspect ratio of most monitors is 4:3. |