Appendix A. Glossary

A RISC (Reduced Instruction Set Computer) architecture developed by Digital Equipment Corporation.

A little application, usually a utility or other simple program.

Transfer files into storage to save space or for organizational purposes.

AT Attachment Packet Interface. ATAPI is the protocol by which CD-ROM drives communicate with a computer system over an IDE interface.

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Although the base two-numbering system used by computers is known as binary, the word often refers to the executable form of a program. Contrast with "source code."

Basic Input/Output System. On PC-compatible systems, the BIOS is used to perform all necessary functions to properly initialize the system's hardware when power is first applied. The BIOS also controls the boot process, provides low-level input/output routines (hence its name), and (usually) allows the user to modify details of the system's hardware configuration.

Short for "bootstrap." The process by which a computer starts running an operating system when power is applied.

A disk used to start a computer.

See Boot.

Complex Instruction Set Computer. A design philosophy for computers whereby the processor is designed to execute a relatively large number of different instructions, each taking a different amount of time to execute (depending on the complexity of the instruction). Contrast with RISC.

Complementary Metal Oxide Semiconductor. A semiconductor technology used in many integrated circuits. Now often used to describe the low-level hardware that contains a personal computer's BIOS setting, and the computer's hardware clock.

When referring to disk drives, the number of different positions the disk drive's read/write heads can take over the unit's disk platters. When viewed from above the platters, each head position describes an imaginary circle of different diameters on the platter's surface, but when viewed from the side, these circles can be thought of as a series of cylinders nested within each other, hence the term. See also Geometry.

A daemon is a program that runs, without human intervention, to accomplish a given task. For example, lpd is a daemon that controls the flow of print jobs to a printer.

When referring to packages, dependencies are requirements that exist between packages. For example, package foo may require files that are installed by package bar. In this example, bar must be installed, or else foo will have unresolved dependencies. RPM will not normally allow packages with unresolved dependencies to be installed.

Software that controls a device that is connected to, or part of, a computer.

See Hard Disk.

Disk Druid is a component of the Red Hat Linux installation program that is used to partition disk drives during the installation process.

A small mass storage device in a removable cartridge, meant to be read/written to, in a compatible drive.

An operating system (usually Linux) that has been packaged so as to be easily installed.

A domain name is used to identify computers as belonging to a particular organization. Domain names are hierarchical in nature, with each level in the hierarchy being separated from other levels with a period (pronounced "dot"). For example, Foo Incorporated's Finance department might use the domain name "finance.foo.com."

Hidden files. Generally system configuration files that are not used often. File names begin with a dot (.) .

See Device Driver.

The act of configuring a computer system to boot more than one operating system. The name is something of a misnomer, as it is possible to boot more than the two operating systems the word "dual" implies.

Enhanced Integrated Drive Electronics, which is a newer version of the IDE interface standard and another term for a particular implementation for IDE interfaces. EIDE makes larger and faster disk drives possible; most systems sold today use EIDE.

The Red Hat Errata contain the most recent information about important updates, fixes, and corrections for Red Hat Linux. View and access errata at http://www.redhat.com/errata.

A segment of a disk drive that contains other partitions. See Partition.

An abbreviation for Frequently Asked Questions. Linux information is often presented in the form of lists of questions and answers called FAQs.

fdisk is a utility program that is used to create, delete or modify partitions on a disk drive.

A filesystem is the method by which information is stored on disk drives. Different operating systems normally use different filesystems, making it difficult to share the contents of a disk drive between two operating systems. However, Linux supports multiple filesystems, making it possible, for example, to read/write a partition dedicated to Windows.

A somewhat historical term for a small mass storage device in a removable cartridge, meant to be read/written to in a compatible drive. See Diskette.

The act of writing a filesystem on a disk drive.

Fully Qualified Domain Name. An FQDN is the human-readable name that includes a computer's hostname and associated domain name. For example, given a hostname of "foo," and a domain name of "bar.com," the FQDN would be "foo.bar.com."

An abbreviation for File Transfer Protocol. Also the name of a program that, as the name implies, permits the copying of files from one system on a network to another.

In networking terms, refers to a device that connects one or more computers on a network to other networks. The device may be specialized hardware (such as a router), or may be a general-purpose computer system configured to act as a gateway.

When referring to disk drives, the physical characteristics of the disk drive's internal organization. Note that a disk drive may report a "logical geometry" that is different from its "physical geometry," normally to get around BIOS-related limitations. See also Cylinder, Head, and Sector.

Group ID. The means by which a user's membership in a group is identified to various parts of Red Hat Linux. GIDs are numeric, although human-readable names are stored in the /etc/group file.

Desktop elements (icons and menus) used to operate your system. An alternative to text commands and function keys.

Groups are a way of assigning specific access rights to certain classes of users. For example, all users working on Project X could be added to group xproj. System resources (such as disk space) devoted to Project X could then be configured to permit only members of xproj full access.

see Graphical User Interface.

A data storage device. A hard disk contains rotating magnetic media (in the shape of disks) that spin rapidly. Small heads float over the surface of each disk, and are used to write and read data to and from the disk as it rotates.

When referring to disk drives, the number of read/write heads within a disk drive. For each platter in a disk drive, there are normally two heads for each platter, one for each surface, although one surface may go unused. See also Geometry.

A hostname is a human-readable string of characters used to identify a particular computer system.

See Internationalization.

Integrated Drive Electronics, which is the name of a standard interface used to connect primarily disk and CD-ROM drives to a computer system. See also EIDE and ATAPI.

Internet Message Access Protocol. A protocol used by certain mail servers.

Company responsible for producing the microprocessors that most commonly appear in PC-compatible personal computers. These processors include the 80386, 80486, and the Pentium line.

The practice of designing and writing programs that can be easily configured to interact with the user in more than one language. Often referred to as "i18n," due to the number of letters between the starting "i" and the ending "n."

IP addresses are the method by which individual computer systems (or from a more strictly accurate interpretation, the network interfaces on those computer systems) are identified on a TCP/IP network. All IP addresses consist of four number blocks, each ranging from 0 to 255, and separated by periods.

Internet Service Provider.

The central core of an operating system upon which the rest of the operating system is based.

When speaking of computers, refers to a collection of routines that perform operations which are commonly required by programs. Libraries may be shared, meaning that the library routines reside in a file separate from the programs that use them. Library routines may also be "statically linked" to a program, meaning that copies of the library routines required by that program are physically added to the program. Such statically linked binaries do not require the existence of any library files in order to execute. Programs linked against shared libraries will not execute unless the required libraries have been installed.

A commonly-used bootstrap loader for Linux systems based on an Intel-compatible processor.

Created Linux in 1991 while a university student.

A versatile system configuration program written by Jacques Gelinas. Linuxconf provides a menu-based approach to system configuration via several different user interfaces.

A full-featured, robust, freely-available operating system originally developed by Linus Torvalds.

A partition that exists within an extended partition. See also Partition and Extended Partition.

Online manual pages.

The master boot record (or MBR) is a section of a disk drive's storage space that is set aside for the purpose of saving information necessary to begin the bootstrap process on a personal computer.

See Master Boot Record.

When referring to computers, memory (in general) is any hardware that can store data for later retrieval. In this context, memory usually specifically refers to RAM.

A commonly-used bootstrap loader for Linux systems based on the Alpha processor.

In Linux, a module is a collection of routines that perform a system-level function, and may be dynamically loaded and unloaded from the running kernel as required. Often containing device drivers, modules are tightly bound to the version of the kernel; most modules built from one version of a kernel will not load properly on a system running another kernel version.

The act of making a filesystem accessible to a system's users.

The directory under which a filesystem is accessible after being mounted.

In TCP/IP networking terms, a name server is a computer that can translate a human-readable name (such as "foo.bar.com") into a numeric address (such as "10.0.2.14").

Network etiquette. Conventions of politeness that are recognized on the Internet.

A netmask is a set of four number blocks separated by periods. Each number is normally represented as the decimal equivalent of an eight-bit binary number, which means that each number may take any value between 0 (all eight bits cleared) and 255 (all eight bits set). Every IP address consists of two parts (the network address and the host number). The netmask is used to determine the size of these two parts. The positions of the bits that are set in the netmask are considered to represent the space reserved for the network address, while the bits that are cleared are considered to represent the space set aside for the host number.

Network File System. NFS is a method of making the filesystem on a remote system accessible on the local system. From a user's perspective, an NFS-mounted filesystem is indistinguishable from a filesystem on a directly-attached disk drive.

A collection of software that controls various resources of a computer.

Files that contain software, and written in a particular format that enables the software to be easily installed and removed.

Pluggable Authentication Modules. PAM is an authentication system that controls access to Red Hat Linux.

A segment of a disk drive's storage space that can be accessed as if it was a complete disk drive.

The partition table is a section of a disk drive's storage space set aside to define the partitions that exist on that disk drive.

Partitions contain a field that is used to define the type of filesystem the partition is expected to contain. The partition type is actually a number, although many times the partition type is referred to by name. For example, the "Linux Native" partition type is 82. Note that this number is hexadecimal.

See PCMCIA.

Personal Computer Memory Card International Association. This organization produced a series of standards that define the physical, electrical and software characteristics of small, credit card-sized devices that can contain memory, modems, network adapters and more. Also known as PC Cards, these devices are mainly used in laptop computers (although some desktop systems can use PCMCIA cards, too).

A diskette required for Red Hat Linux installations that require the use of a PCMCIA device during the install.

The set of identifiers that control access to files. Permissions consist of three fields: user, group, and world. The user field controls access by the user owning the file, while the group field controls access by anyone matching the file's group specification. As the name implies, the world field controls access by everyone else. Each field contains the same set of bits that specify operations that may or may not be performed, such as reading, writing and executing.

Pretty Good Privacy. PGP is an electronic privacy program which helps you ensure privacy by letting you encrypt files and e-mail. The encryption technology employed by PGP is very strong. PGP was created by Phil Zimmermann, and depends on public key cryptography for its effectiveness. Public key cryptography is a procedure in which users exchange "keys" to send secure documents to each other. For more on PGP, go to http://www.pgp.com.

Parallel Line Internet Protocol. PLIP is a protocol that permits TCP/IP communication over a computer's parallel port using a specially-designed cable.

Post Office Protocol. A protocol used by certain mail servers.

A somewhat convoluted abbreviation for Portable Operating System Interface. A set of standards that grew out of the UNIX operating system.

Point-to-Point Protocol. A protocol that permits a dialup connection to an Internet Service Provider.

A process (in somewhat simplistic terms) is one instance of a running program on a Linux system.

A PS/2 mouse gets its name from the original computer in which this type of mouse was first used — the IBM PS/2. A PS/2 mouse can be easily identified by the small, round connector at the end of its cable.

An acronym for Random Access Memory. RAM is used to hold programs while they are being executed, and data while it is being processed. RAM is also volatile, meaning that information written to RAM will disappear when the computer's power is turned off.

A virtual drive which uses part of a computer's RAM to store data. A RAM disk provides quick access to information, but unlike written data, that data in a RAM disk is lost when the computer is turned off.

To restart the boot process. See also Boot.

A software company that produces and markets software, including Red Hat Linux.

Also RHN. Internet solution for downloading and installing/updating packages on your system. Consists of Red Hat Update Agent and Red Hat Network Web Application.

Part of the Red Hat Network, Red Hat Update Agent is a standalone application used to install/update packages on your system.

see Red Hat Network.

An abbreviation for Read Only Memory. ROM is used to hold programs and data that must survive when the computer is turned off. Because ROM is non-volatile; data in ROM will remain unchanged the next time the computer is turned back on. As the name implies, data cannot be easily written to ROM; depending on the technology used in the ROM, writing may require special hardware, or may be impossible. A computer's BIOS may be stored in ROM.

The name of the login account given full and complete access to all system resources. Also used to describe the directory named "/"as in, "the root directory."

RPM Package Manager (yes, it might seem strange, but that IS correct). RPM enables the installation, upgrading and removal of packages (software programs that together form the Red Hat Linux operating system).

RPM Package Manager (yes, it might seem strange, but that IS correct). RPM enables the installation, upgrading and removal of packages (software programs that together form the Red Hat Linux operating system).

An abbreviation for Small Computer System Interface, SCSI is a standard interface for connecting a wide variety of devices to a computer. Although the most popular SCSI devices are disk drives, SCSI tape drives and scanners are also common.

See SMB.

A serial mouse is a mouse that is designed to be connected to a computer's serial port. A serial mouse can be easily identified by the rectangular-shaped connector at the end of its cable.

A system call that can be used to set the GID of a process. Programs can be written using setgid such that they can assume the group ID of any group on the system.

A system call that can be used to set the UID of a process. Programs can be written using setuid such that they can assume the user ID of any process on the system. This is considered a possible security problem if a program is "setuid root."

Normally, each user's password is stored, encrypted, in the file /etc/passwd. This file must be readable by all users so that certain system functions will operate correctly. However, this means that copies of user's encrypted passwords are easily obtained, making it possible to run an automated password-guessing program against them. Shadow passwords, on the other hand, store the encrypted passwords in a separate highly-protected file, making it much more difficult to crack passwords.

Normally, each user's password is stored, encrypted, in the file /etc/passwd. This file must be readable by all users so that certain system functions will operate correctly. However, this means that copies of user's encrypted passwords are easily obtained, making it possible to run an automated password-guessing program against them. Shadow passwords, on the other hand, store the encrypted passwords in a separate highly-protected file, making it much more difficult to crack passwords.

Command interpreter.

Serial Line Internet Protocol. SLIP is a protocol that permits TCP/IP communication over a serial line (typically over a dial-up modem connection).

Server Message Block. SMB is the communications protocol used by Windows-based operating systems to support sharing of resources across a network. Also known as Samba.

Simple Mail Transfer Protocol. A widely used definition for how to transfer mail over a network.

The human-readable form of instructions that comprise a program. Also known as "sources." Without a program's source code, it is very difficult to modify the program.

A RISC (Reduced Instruction Set Computer) architecture developed by Sun Microsystems.

Also known as "swap space." When a program requires more memory than is physically available in the computer, currently-unused information can be written to a temporary buffer on the hard disk, called swap, thereby freeing memory. Some operating systems support swapping to a specific file, but Linux normally swaps to a dedicated swap partition. A misnomer, the term swap in Linux is used to define demand paging.

A system call is a routine that accomplishes a system-level function on behalf of a process.

An abbreviation for Transmission Control Protocol/Internet Protocol, TCP/IP is the networking standard used on the Internet today.

See Linus Torvalds.

User ID. The means by which a user is identified to various parts of Red Hat Linux. UIDs are numeric, although human-readable names are stored in the /etc/passwd file.

A set of Linux-like operating systems that grew out of an original version written by Ken Thompson and Dennis Ritchie of Bell Telephone Laboratories.

The act of revoking access to a filesystem. (Note that the program that unmounts filesystems is called umount.)

see Red Hat Update Agent.

Virtual consoles provides multiple "screens" on which a user may log in and run programs. One screen is displayed on the computer's monitor at any given time; a key sequence is used to switch between virtual consoles.

A standardized on-screen representation of a control that may be manipulated by the user. Scroll bars, buttons, and text boxes are all examples of widgets.

Also known as "X," this graphical user interface provides the well-known "windows on a desktop" metaphor common to most computer systems today. Under X, application programs act as clients, accessing the X server, which manages all screen activity. In addition, client applications may be on a different system than the X server, permitting the remote display of the applications graphical user interface.

A free implementation of the X Window System.