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LinuxGlossary

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a2psA Linux utility for converting text files into files in the Adobe PostScript format.acceleratedThe term for video cards that have their own onboard processors, with consequent enhanced performance.address masqueradingIn Linux, a security feature that allows system administrators to use a single Internet-connected server to act as a gateway. This machine uses a different name from the true hostname, enabling internal hosts on that domain to remain hidden.aliasAn alternative, usually shorthand, name for a particular entity, such as a mail address or a command. In general, an alias can be for a file, device, or other object, but in Linux it generally refers to a shorter version of a command.aliasingThe creation of fictitious but functioning email addresses. An alias address links directly to other, "real" e-mail accounts in a specified domain, and any messages sent to it are automatically placed in the linked accounts.ApacheA free web server that is used to host over 60 percent of world web sites. The source code is freely available and can be modified by anyone. Apache was originally developed for UNIX, was adapted for Linux, and is now widely used by Linux systems. Its main advantage is that it enables Internet service providers to run multiple web servers on one machine.APIAn acronym for Application Programming Interface, a specification that allows access to the functionality of a library or other system resources when writing a program.Application Programming InterfaceSee API.aproposA command that provides documentation and manual pages relevant to a chosen keyword.apt-getA tool that enables users to select sources from which to get new packages.argumentA value or option that is used by a command when executing. This can include information that is operated on by the command or information that modifies the behavior of the command.ASCIIAcronym for American Standard Code for Information Interchange, a binary code that is used for text as well as communications and printer control.AT commandsCryptic commands that make up an INIT string used for modem configuration.authenticationThe process of identifying users' machines before allowing a connection to be established. Two commonly used authentication protocols are PAP (Password Authentication Protocol), used by a client to authenticate a server, and CHAP (Challenge Handshake Authentication Protocol), used by a server to authenticate a client.autoA default option for a device that allows it to be automatically mounted at boot time.autoprobeA process that discovers device configuration information.autoresponderA program that responds with a prewritten message when a user submits an e-mail. It is generally used to confirm receipt of a message.awkA utility that allows the user to search for, filter, and manipulate strings of characters in text files.Back to topB

backgroundThe environment in which certain jobs have no priority over the system's resources and only run when resources are not being used for a job in the foreground. Linux can run an unlimited number of jobs in the background.backupA copy of the filesystem or part of the filesystem that is stored on another medium and can be used to recreate the original.bad sectorsA faulty portion of a disk that cannot be used dependably by the operating system for storing information. As these sectors are unreliable, the hard drive does not allow data to be written to them.bashAcronym for Bourne again shell, the default shell in Linux. See also csh and pdksh.batchA job that consists of a series of processes in a queue executed sequentially.Baud rate1. Based on the Baud unit, which is defined as one symbol (state or level transition) per second. 2. Defined as one electronic change per second, this is one of the main methods of measuring the rate of data transmission.bgA command used when a job is stopped, to send it into the background.binary1. A type of program that has already been compiled and is ready to run. 2. A base 2 number system having exactly two unique digits, on which computers are based.BIOSAcronym for basic input/output system, firmware that loads the operating system after ensuring that the hardware is functioning properly. The BIOS is located on a ROM chip on the motherboard.blockThe term for specific piece of information held on a storage device, such as a disk drive. Common block sizes are 512 and 1024 bytes.block deviceA type of storage device that handles data in units of a particular size, known as blocks.block special fileA UNIX or Linux file which points to the device driver for a device, such as a disk drive, that requires data in a block, or blocks.boot floppyA floppy disk that contains a bootable operating system.boot loaderA program that finds and loads the kernel at boot time.boot managerA program that loads the operating system and may let the user choose which operating system is booted.bouncedAn e-mail that cannot be delivered and which is returned to the sender's mailbox via the mailer daemon.breakA command that exits completely from the innermost level of a loop. It enables users to exit embedded loops easily.broadcast addressAn address used to reach all of the nodes on a network.bufferA temporary storage area, usually in RAM.built-in commandA command that is part of the shell program.Back to topC

cable lockA hardware device used for securing computers and other devices so that they can't be moved.caching nameserverA server that stores resolved DNS addresses to save time when these addresses are next needed.caseA command that is used to create a conditional statement in a shell script to match a defined pattern to a string.catA program that sends the contents of a file to the standard output.CGAAbbreviation for Color/Graphics Adapter, the first video display standard for IBM PCs. It has been superseded by VGA.CGIAbbreviation for Common Gateway Interface, a standard for data transfer between a server and a CGI-compatible program. CGI files are executables that run on web pages.character special fileA UNIX or Linux file which points to the device driver for a device, such as a terminal, that requires data in characters.charactersThose symbols which require one byte to store them, including all the ASCII and extended ASCII characters.chatA Linux utility for automating conversations between a computer and its modem, thereby allowing the automatic Point-to-Point Protocol (PPP) connections. It is possible to specify a chat script via the command line, but it is more common to store the information for an automated connection in a plain text file containing sets of expect-send strings. This allows reactions to various modem responses to be anticipated to enable automatic connection.chgrpA command that changes the group that a file belongs to.child processA process that starts within an existing process. The existing process becomes the parent process.chipset1. A particular configuration of processors and associated hardware, mounted on a single circuit board.2. In the context of video cards, the term for the logic circuit that controls the card. Also called the accelerator or the video coprocessor.chmodA command that modifies permissions on a file or directory.chownA command that changes the owner of a file or directory.client/server computingA computing model where the network is split into clients, who request services, and servers, which provide the services and handle processing and data.CMOSAcronym for complementary metal oxide conductor, a 64 byte memory component on which the BIOS hardware configuration settings are stored when the machine is powered off.commandAn instruction to the computer to perform a task composed of a command name, arguments, and options.command interpreterAn alternative term for a shell.command lineThe computer interface where commands are entered.command substitutionThe substitution of the results or output of one command for the input of another. This allows a series of commands to be linked in the same command line.commercialA type of software that must be purchased before use. See also freeware.Common Gateway InterfaceSee CGI.compileThe process of turning high-level source code into executable object code.compilerA program that reorganizes source code and translates it into a binary or executable program.conditional statementA statement that enables shell scriptors to control the program flow and force the shell to choose between alternative actions according to the outcome of specific tests. It is included anywhere in a shell script.configA program that is a basic kernel configuration method. It supplies a simple text-based interface.consoleA hardware device, a computer with keyboard and screen that allows input of information or commands.continueA command that causes the program to skip the remaining commands in an iteration of the loop, but stay in the loop. It transfers execution to the bottom of the body of the loop.cpA command that is used to copy files.cpioA utility that permits the copying of files. It is available on every Linux system. It can create an archive containing multiple files or copy a directory hierarchy.crackerA person who breaks into computer systems.cron jobA job that is stored in the system to be executed at a specified time in the future.cryptographyThe study of transforming data into an unreadable format. The only way to read the data is to be in possession of a particular key a large number that can unlock the data.cshAbbreviation for C shell, one of the shells available in the Linux operating system. See also bash and pdksh.CTRL+CThe command used to stop the job that is running in the foreground.CTRL+ZThe command used to pause a job. The job will continue from the same point if it is restarted in the background or foreground.cylinderOn a hard disk, the sum total of every track with the same track number on every disk surface.Back to topD

daemonA process that is usually initiated at boot time but then runs in the background until it's requested.datagramSee dgram.DebianA free distribution of Linux that is developed openly by developers over the Internet.debuggingThe process of finding and removing program errors.default routeIn networks, the route that information packets will take if no other route is specified.demilitarized zoneSee DMZ.denial-of-serviceAn attack on a computer system that results in depriving users of a specific service or resource.dependencyThe relationship between a compiled file and the file from which it is compiled. For example, an object or executable file depends on a source file.desktop environmentA group of utilities that provides users with a GUI interface for easy file management.destructive partitioningPartitioning that deletes all pre-existing partitions and their contents. See also non-destructive partitioning.deviceAny hardware item that is part of or attaches to a computer. In Linux, device can refer specifically to hardware that inputs or outputs data.device nameA name used to represent the physical address of a hardware device.dfA command that displays the disk space usage of storage devices.dgramAbbreviation for datagram, a data packet sent by the UDP network protocol.DHCPAbbreviation for Dynamic Host Configuration Protocol, a software package that automatically assigns IP addresses to client stations logging on to a TCP/IP network.diffA command used to compare two files and display the differences between them.directiveIn an Apache configuration file, an instruction used to configure a specific aspect of server operation.directoryA type of file that contains other files and a list of the names and other information about the files it contains.disk platterThe data storage area of a hard disk.DISPLAYA variable that decides where display graphics will be painted.display managementA process in which the X server software organizes the display area into windows and paints graphics to the correct windows.distributionA software package that contains all the software necessary to install and run a customized version of Linux.DMAAbbreviation of direct memory access, this is a technology that allows data to pass between a device and the computer's main memory via DMA channels without the intervention of the processor.dmesgA command that displays boot time messages.DMZAn abbreviation of demilitarized zone, a buffer zone between a company's internal network and the Internet.DNSAbbreviation for Domain Name System, a set of hierarchical databases that locates and maps domain names to their corresponding IP addresses. This directory service is crucial to the delivery of e-mail.Domain Name SystemSee DNS.dotted quadsAnother name for IP addresses, because they consist of groups of four bytes separated by dots.downstreamA term that indicates the direction of data, meaning towards the output device.dpkgA tool that enables users to remove and install packages, and retrieve general information about the packages.driverA software program that enables interaction between software and hardware by translating generic input/output commands into specialized code.dselectA tool that is used to fetch, install, or remove packages.duA command that displays the amount of space used by any given file or directory.dual bootA computer configuration that allows you to start up your computer with either of two different operating systems. The dual boot feature is contained within one of the operating systems.dumpAn archive utility that can carry out various types of backup from a full backup to different levels of incremental backups.dynamic fileA file that contains data that changes frequently. Examples include user files, log files, and temporary files.dynamically linked programA program that contains sub routines that refer to shared libraries stored elsewhere.Back to topE

echoA command that displays specified text.edA line-based text editor that was developed for use with teletype terminals and allows the user to view and work on only one line of text at a time. In Linux, it usually operates within vi.edquotaA command that allows the user to define the amount of space a given user or group may use.egrepA command that searches a specified file or files for an extended regular expression pattern. See also grep and fgrep.EISAAcronym for Extended ISA, a PC bus standard that extends the 16-bit ISA bus to 32 bits and provides bus mastering.emacsA screen-oriented text editor that offers an extensive list of features.envA command that directs the shell to display only a selection of the environment variables.environment variableIn Linux and other UNIX-like systems, a variable that contains a value that determines some aspect of the appearance or operation of the shell. Although many environment variables are configured automatically, it is possible to change the settings manually using the set command. See also variable.escapeA process in which a metacharacter is treated as regular text.EthernetThis is the most commonly used LAN protocol and forms the basis of the IEEE 802.3 standard for the lower networking layers of the Open Systems Interface model. 10Base-T and 100Base-T are the two main Ethernet network types and allow data transfer rates of 10 Mbps and 100 Mbps respectively.eventA term that refers to a single command stored in the history file.event numberA unique number given to each event listed in the history file.executable fileIn UNIX and Linux, a file that has at least one of its execute permission bits set and that can therefore be invoked as a program.executeTo invoke a program.exportA process in which a variable is extracted from a sub-shell or process and is made available as an environment variable to all of the shell.extended partitionA primary partition that is formatted to hold logical partitions. There can be only one extended partition per hard disk. See also logical partition.Back to topF

facilityA term used to refer to services when configuring how they are to generate log files.fcA command that displays past events on the terminal screen.FDDIAbbreviation for Fiber Distributed Data Interface, an ANSI standard token-passing network that uses optical fiber cabling.fdiskA program used to manage disk partitions.fgA command that moves a job from the background to the foreground.fgrepA command that searches a specified file or files for a simple string or list of strings. See grep and egrep.FHSAcronym for Filesystem Hierarchy Standard, a set of requirements and guidelines for file and directory placement under Linux and other UNIX-like operating systems.FIFOAcronym for First In First out, a special file in a UNIX or Linux filesystem that acts just like a pipe and is used to pass information between processes.file1. A collection of related information manipulated as a single entity.2. In Linux, a command that examines a file and displays what kind of file it is.filesystemThe storage structure for files on a hard disk. Each filesystem is associated with a specific part of the directory tree. The primary filesystem or root filesystem corresponds to the / directory.Filesystem Hierarchy StandardSee FHS.Filesystem StandardSee FSS.filterA command that operates on a text stream.findA command that searches the filesystem for files.fipsA program designed to split an existing DOS partition without deleting the data on it.firewallA security system that restricts the type of connection that can be established with a network, usually based on the data or application type.firmwareA piece of software that is built into a hardware device.First In First OutSee FIFO.forA loop command that executes once for each item in an argument list. See also while and until commands.foregroundThe environment in which a certain job has priority over the system's resources. Linux can run only one job at a time in the foreground.formattingA process in which partitions on a drive are created to store files for a particular operating system.forwardingIn Linux and UNIX systems, a form of aliasing available to individual sendmail users that allows mail to be redirected to one or more users, to a file, to a program, or to a combination of these.freewareA type of software that may be under copyright but can be used without charge.fsckA Linux program that checks filesystems and corrects errors. It can be run only on unmounted filesystems or filesystems that are mounted as read-only. It can be run automatically at boot time.FSSAbbreviation for Filesystem Standard, a standard hierarchy for filesystems. The FSS specifies locations for system files, user applications, data files, and configuration settings that are implemented across different Linux distributions.functionA series of commands within a script or program that is given a name and can be invoked and executed independently of the rest of the code in the program.Back to topG

gawkA text-manipulation utility, the GNU version of awk.General Public LicenseSee GPL.GhostScriptA free interpreter for the Adobe PostScript formatting language that allows non-PostScript-enabled printers to print PostScript files.GIDAbbreviation of group identification number, a number Linux uses to track users.global variableA variable that applies everywhere except where a variable by the same name is defined locally using the local keyword.GNOMEAcronym for GNU Network Object Model Environment, a standard Linux desktop environment, composed completely of open-source software.GNUPseudonym used by the Free Software Foundation, the creators of the GNU/Linux operating system.GNU Network Object Model EnvironmentSee GNOME.gpasswdA command that adds users to a group.GPLAbbreviation for General Public License, a license developed by the Free Software Foundation that applies to Linux and other open source software. It allows for the free use, modification, and distribution of software.grace periodThe period of time a user is given to comply with a warning. In Linux, this usually refers to the time between a user exceeding their soft limit and having their account disabled.grepA text filter that searches files to find particular strings.groupaddA command that creates a new group.groupmodA command that modifies the group name or its GID.grpquotaA command used to allocate the disk space that can be used by groups.GUIAcronym for Graphical User Interface, a type of interface that presents users with graphical representations of files, directories, and applications for ease of use. The alternative is a command-line interface.gunzipA utility used to uncompress a tarball and extract the archive.gzipThe utility used to compress a tarfile and create a tarball.Back to topH

hard limitThe amount of disk space a user can take up. This is the maximum that is actually available to the user, not just the space they are authorized to use. See also soft limit.hard linkThe connection between files that share an inode.headA command used to display the beginning of a file.head of a streamAn application that is generating data. A data stream is said to move from the application at the head of the stream to the output device downstream.helpA command used to inform the user about the commands that are built into the shell.historyA command that displays all the events in the history file.history fileA file that stores a record of commands that are issued to the shell. It is possible to modify the size of this file and the number of commands it records.horizontal scan rateAlso known as the horizontal refresh rate, a measure of how many scan lines of pixels a monitor can display in one second, expressed in kilohertz (kHz).hostA term used to refer to any computer on a network.hosts.allowAn access control file that contains a list identifying who can have access to specific services. See also hosts.deny.hosts.denyAn access control file that contains a list identifying who is disallowed access to specific services. See also hosts.allow.How-ToThe name given to a type of general Linux documentation.Back to topI

I/O addressAn abbreviation for input/output address, a unique memory address that defines a memory region to be used exclusively by a hardware device and used to reference all other addresses within the region in communication between the device and the operating system.I/O base addressSee I/O address.ICMPAbbreviation for Internet Control Message Protocol, which is a protocol used mainly for diagnostic purposes. The other IP protocols, UDP and TCP, are the basic methods of communication between programs running on different machines.IDEAbbreviation for integrated device electronics, a standard peripherals interface that allows for a maximum of two devices to be connected to a single cable. IDE devices are so named because their controller electronics are built into the actual device, although this is also true of most SCSI devices.ifA command that is used to handle various types of arguments to create a conditional statement in a shell script. These argument types include command output, variable values, and file status.ifconfigA program used to configure and monitor network interfaces.imageThe compressed Linux kernel. At boot time, the image is decompressed, loaded into memory, and executed.IMAPPronounced "eye-map", the acronym for Internet Message Access Protocol, a protocol that listens on port 143 and is responsible for retrieving messages from the destination server. This protocol initially only downloads the header of an e-mail rather than the whole message. IMAP4 is more advanced than POP3 and supports keyword searching and online, offline, and disconnected message access.Industry Standard ArchitectureSee ISA.inetd daemonThe Internet services daemon, also called the super server, a program developed by Berkeley Services Distribution to reduce the system load entailed in UNIX and Linux by running multiple standalone daemons. It is initiated at system startup and listens to multiple network ports at the same time for incoming requests for network services. As soon as a service is requested, inetd invokes the appropriate server to provide the service before continuing to listen for new requests.inetd.confA configuration file for the inetd daemon that contains a list of network services that inform inetd which ports to listen to and which server programs to run. Each entry in the file defines the parameters for a single service.infoA command that displays documentation in a hypertext format.INIT stringA sequence of AT commands that are used to configure modems.initial RAM diskContains the information required for booting the kernel. It is created in RAM memory and enables the kernel to access the boot device and continue the boot process.inodeA resource that contains information about a file and tracks the location of data within the file. Each file has its own inode.inode numberA unique identification number the kernel assigns to each physical file in the system.insmodA command for managing modules that allows the user to load a module manually.integrated device electronicsSee IDE.interactive1. A term that means the program is able to accept user input. 2. An adjective that describes a foreground or background process initiated from, and controlled by, the shell.interfaceThe point at which two entities meet. This can be the user/computer interface, which could be a command line or a graphical environment. It can also refer to the connection between a host computer and a network.Internet Control Message ProtocolSee ICMP.Internet Message Access ProtocolSee IMAP.interruptA signal that indicates that some event has occurred within a computer. Hardware interrupts are usually exchanged between devices in the system and the CPU.interrupt request lineSee IRQ.IP addressA 32-bit number which identifies a computer or device on a TCP/IP network. The address itself can be expressed in binary, as four eight-bit octets separated by a period, or more commonly in dotted-decimal notation, for example 94.16.125.128, where each dot-separated part can have the value 0-255.IP chainA set of rules for packet handling, implemented as part of a firewall.IRQAn abbreviation for interrupt request line, a hardware line over which an interrupt can be sent from a device to the CPU. There are 16 IRQs in most PCs today.ISAAcronym for Industry Standard Architecture, a 16-bit expansion bus commonly used in PCs. Plug-in boards use it to control sound, video display, and other peripherals.isapnpA tools package that allows users to implement the instructions in the configuration file.Back to topJ

jobA series of separate, related processes started from a single command line.job IDThe number assigned automatically to a print job in a queue that allows it to be identified individually.job numberA number that is assigned to each job when it is sent into the background.jobsA command used to display the status of jobs running in the background.jumper settingsThe various options that allow you to configure the operation of a hardware device physically by placing prongs on its electrical contacts.Back to topK

K Desktop EnvironmentSee KDE.KDEAbbreviation for K Desktop Environment, a group of programs that provides users with a free, open-source GUI environment that runs on most varieties of UNIX.kernelThe core part of an operating system that communicates with hardware and regulates processes.kernel spaceAn area of the system architecture that handles all of the low-level processes.kerneldA Linux daemon that supports the automatic loading of a module or modules. It was introduced in version 1.3 of the Linux kernel. In 2.1 kernels, kerneld is replaced by kmod, which performs the same functions but is part of the kernel.keyAn item that identifies a user, allowing them to access and modify files.keymapA file that defines the correspondence between characters and keys on the keyboard.killA command used to terminate processes.killallA command used to terminate a selection of processes.kmodSee kerneld.Back to topL

lastA command that searches and lists records of logins and logouts. Records can be narrowed to a given user or terminal.lastbA command that searches and lists records of failed login attempts.ld.soA shared object dynamic linker that reads the routines in the shared libraries at runtime along with the code in the program file.ldconfigA utility that enables users to configure shared libraries.lddA utility that lists all shared libraries that a program depends on.lessA command used to display the contents of a file.libraryA collection of routines and functions that are made available to programs.LILOAcronym for Linux Loader, a standard Linux boot-up program.linkA pointer to a file.linmodemA software-based modem specifically developed for use in the Linux operating system, in which much of the hardware functions are carried out by the chipset instead of specialized modem electronics.Linux1. A kernel for an operating system that was released by Linus Torvalds. 2. A multi-tasking operating system that is based on the Linux kernel.Linux LoaderSee LILO.literal characterA symbol that has no specific meaning to an operating system. See also metacharacter.lnA command that creates a link.local variableA variable that applies only within a particular function or script.locateA command that finds items in the filesystem by checking the locate database.logA file that details the operation of a process.logical AND operatorA term for an operator used in many programming languages that relates two expressions on a logical basis. With the logical AND operator, the combined result of the two expressions returns true only if both expressions are true.logical OR operatorA term for an operator used in many programming languages that relates two expressions on a logical basis. With the logical OR operator, the combined result of the two expressions returns true if either expression is true.logical partitionAn additional partition within an extended partition. It is possible to have up to 16 logical partitions per hard disk.logrotateA command that allows automatic rotation, compression, removal, and mailing of log files.loopback addressThe IP address 127.0.0.1, used for internally testing the IP interface on a local machine.loopback deviceA system that allows a computer to address itself directly without having to go through a network.loopback interfaceA special type of network interface that allows a machine to make connections to itself.looping statementA code construction that executes a series of commands repeatedly until or while predefined conditions are met.lpcA utility that is used to manage print queues. It can produce status reports on printers, the queues associated with them, and on individual users.lpqA command that is used to query print jobs in Linux.lprA program that is a popular Linux print client.lprmA command that is used to remove a print job.lsA command used to list the files in a directory.lsmodA command for managing modules that lists the modules that are currently loaded.Back to topM

mail forwarderA mail process that sends the mail to the server and does nothing else.mail queueIn Linux, a directory that stores messages for later delivery when the first attempt fails.mail transfer agentSee MTA.mail user agentA program for managing e-mail.mailer daemonA program activated by an e-mail that bounces. It ascertains why the mail can't be delivered and reports the reason to the sender.make1. A command that instructs the compiler to use a set of rules drawn up by the programmer. 2. The program that provides sequence control when compiling source code. Its configuration file, the Makefile, contains information about dependencies between individual files.make bzImageA command that compiles a compressed kernel image file. It is one of three commands that are used to compile a new kernel. See also make clean and make dep.make cleanA command that removes any old object files and temporary files created during previous compilations. It is one of three commands that are used to compile a new kernel. See also make dep and make bzImage.make depIn Linux, a command that builds the dependency list. It is one of three commands that are used to compile a new kernel. See also make clean and make bzImage.make installA command that places the compiled binaries in the correct location after the make utility has run.make targetsA particular case of the make command instructing the compiler to use a section of the makefile.MakefileA file that contains the commands required to compile source code into its final executable form.manA command used to call up information about system commands.map installerA program that installs and configures the boot loader. It does this by reading the configuration file containing information such as the location of the kernel and the default boot disk.MAPIAcronym for Messaging Application Program Interface, a Microsoft program that allows mail to be exchanged between different e-mail applications. MAPI works from a dynamic link library (DLL) that consists of a set of C language functions. Microsoft applications that use MAPI include Outlook, the Exchange client, and Schedule.mapping1. The process by which items in a stored set of data are linked to related items in hardware or in another, differently encoded set of data. 2. In UNIX and Linux, the translation process that changes virtual addresses into real addresses.maskA filter that only accepts certain values. It can also mean the permissions set for a file or directory.master boot recordThe first sector of the hard disk that takes control of the boot process for a short while. It holds the partitioning information of the disk.MBRSee master boot record.MD5 ChecksumA 128-bit number, used by RPM to express a package's content mathematically. RPM creates an MD5 checksum for every file and package and stores these in its database. Any changes can then be detected by comparing the current number against that stored in the database.MDAAbbreviation for mail delivery agent, a program that transfers an email from the receiving MTA to the recipient's mailbox.menuconfigA program that offers a text-based menu that is navigated using the arrow keys. It offers colored text and lists options.metacharacterA symbol that has a specific meaning to an operating system, for example wildcards.MIBAcronym for Management Information Base, a database object that contains information associated with a networked device.MIMEAcronym for Multipurpose Internet Mail Extensions, a specification that supports eight-bit character sets and multipart files and that allows users to send and receive e-mails consisting of audio, video, and graphics files.mkbootdiskA Linux utility that creates a boot floppy.mkdirA command used to create a new directory.mke2fsA program used to format partitions so they will hold Linux files.mkfsA command that is used to make filesystems.modinfoA command for managing modules that provides information on currently loaded modules.modprobeA command for managing modules that checks for dependencies in the module database and loads any modules that might be needed before loading the requested module.moduleIn Linux and UNIX, a device driver that can be added to or removed from memory while the system is running. A module can either be sourced externally or it can form part of the official kernel sources. It is usually easier to debug than a static kernel driver. Certain modules will work only when they are backed up by functions provided by other modules or other parts of the kernel. Modules are also referred to as loadable device drivers.modules.confA file that contains NIC configuration settings.moreA command used to display the contents of a file one page at a time.motifA standard GUI interface that is often installed across a network so all workstations will have the same general appearance.mountA process that adds a device to the filesystem.mount pointThe point in a directory at which a file or filesystem is made available to that directory.MTAAbbreviation for mail transfer agent, a program that transfers e-mails over the Internet.MUAAbbreviation for mail user agent, a program that allows users to create and receive e-mail as well as display, file, and print them in their mailboxes.multicastingThe term for two-way communication between multiple sites on the Internet.mvA command used to change the name or location of a file.Back to topN

named pipeAlso known as a FIFO, an actual file in a UNIX or Linux filesystem that is used to pass information between processes.nameserviceThe process of resolving name-based Internet addresses into numeric IP addresses.NATAcronym for Network Address translation, a process which allows computers on a local network to be given an Internet address.netmaskAn address range used to determine the network that an IP address belongs to.network addressA string of numbers that identifies an element in a network.Network Address translationSee NAT.network classThe highest level at which an IP address is organized. There are five such levels, A through E, and each level has a specific purpose.network daemonA program, usually initiated at system startup, which runs in the background and listens and responds to requests at a specific port. The network daemon's job is to provide a specific networking service such as Telnet or FTP.Network File SystemSee NFS.Network Information ServiceSee NIS.network interface cardSee NIC.network portsLogical rather than physical connections that transfer information into and out of a machine.NFSAn abbreviation for Network File System, a file system that allows users to access files on remote hosts as if they were local.NICAn abbreviation for network interface card, a hardware device that allows a computer to communicate with a network.niceA command that sets the priority of a process and decides how much CPU time it is allocated.nice valueA value indicating a program's scheduling priority, with -20 being the highest and 19 being the lowest. The default value is 10.NISAcronym for Network Information Service, a method of providing key information such as passwords, login names, home directories, and group names available to all machines on the network via a network lookup service consisting of databases and processes.nlA command that adds line numbers to a file.nmdbA daemon that acts as name server for Samba, providing relevant information when requested. It must be running to use Samba. See also smbd.NMSAbbreviation for network management station, a client program that uses the SNMP protocol to communicate with server programs that reside on networked devices.noclobberA system variable that determines whether files can be overwritten by new files of the same name. Noclobber is off by default, which means files may be overwritten.nonacceleratedThe term for video cards that rely entirely on the host computer for processing capabilities.non-destructive partitioningPartitioning that creates new partitions from existing ones without deleting data. See also destructive partitioning.Back to topO

octalA base-8 numeric system.odA command that dumps files.OIDAbbreviation for object identifier, a number that identifies a particular data set or parameter in an MIB.OPEN LOOKA standard GUI interface, developed by Sun, which is often installed across a network so all workstations will have the same general appearance.open sourceAny source code of a program or operating system that is made freely available to all developers for use, modification, and distribution. Central to the open-source rationale is the concept of peer review of code, which eliminates bugs on a cooperative basis and results in a more useful product for everyone.optionAn instruction that changes the implementation or behavior of a command.OS/2An IBM operating system developed for use in PCs.ownerA user with complete access rights to a file.Back to topP

packageA self-contained, self-installing set of files and programs.package managementA type of software tool that makes it easier to update system components.packetA unit of data transmitted over a network.PAMAcronym for pluggable authentication modules, a system that allows you to implement authentication methods independently of the application requiring authentication.parent processThe process within which a new process is created. The new process is called the child process ; the old process becomes the parent.partitionA reserved part of a disk or memory that is set aside for some purpose. All hard disks must be partitioned before installing an operating system, even if the entire disk space is to be left as a single partition. The partitioning process tells the operating system how the disk space is to be used. See also primary partition, extended partition, and logical partition.passwd1. A command that creates password entry information for users.2. A file that contains password entry information for a specified username.patchA file used to upgrade a program to a newer version. It is generated with the diff command, which creates a file containing the differences between the new and old versions.path1. Collection of directories defined by the PATH environment variable, within which the shell looks for commands (also known as the search path).2. A complete filename specified relative to the root directory (also known as a pathname).patternA collection of characters, including wildcards, which constitutes a search term.PCIAcronym for Peripheral Component Interconnect, a bus standard designed by Intel. It allows data to be transmitted between the CPU and peripheral devices at throughput rates of 133 MBps and upwards, it supports 32-bit and 64-bit data paths, and it works in conjunction with the ISA bus. It also offers Plug and Play support.PCMCIAAcronym for Personal Computer Memory Card International Association, an organization that has developed standards governing attachments for peripheral devices. These attachments are referred to as PC cards. They come in three different widths and are the size of a credit card.pdkshAn abbreviation for the version of the Korn shell used by Linux. See also bash and csh.Peripheral Component InterconnectSee PCI.permissionThe element of a file that determines which users may access or change it.PGPAbbreviation for Pretty Good Privacy, a public key cryptography system used by RPM to verify package authenticity.picoAn abbreviation for Pine Composer, a screen-oriented text editor that offers basic text editing, paragraph justification, searching, block cut and block paste, spell checking, and a file browser.PIDAn abbreviation for process identifier, the unique number given to each process when it is executed.Pine ComposerSee pico.pingA networking utility that tests whether a specific IP address can be reached. It is primarily used to verify Internet connections.pipingA process that takes the output of one program or command and connects it to the input of another. This allows a series of commands to be linked in the same command line.plug and playA method used to auto-configure devices.pluggable authentication modulesSee PAM.pollA query to SNMP agents sent out by an NMS.POPAcronym for Post Office Protocol, a mail collection and storage protocol.POP3Acronym for Post Office Protocol version 3, a retrieval protocol that is primarily used for offline message access. It transfers mail from the destination server to a user's mailbox. When the user downloads a message, it is stored locally and deleted from the server.portA logical connection point to the network.Portable Operating System InterfaceSee POSIX.portmapperA daemon on an NFS server that can ignore all requests except those from approved clients.POSIXAcronym for Portable Operating System Interface, a standard that defines a common set of interfaces for UNIX operating systems. Linux is intended to be a POSIX-compliant operating system.POSTAcronym for power-on self test, a series of tests carried out by the BIOS during the boot-up process. These tests ensure that the machine's hardware devices are working properly.Post Office ProtocolSee POP and POP3.PostScriptA page descriptor language specifically created by Adobe Systems Inc. for high-end laser printers designed to handle the Adobe PostScript format. It offers high-quality output because the language can scale the output according to the printing needs.PPPAbbreviation for Point-to-Point Protocol, the most common protocol for transferring data packages across a serial link. PPP links machines in a peer-to-peer relationship there is no real difference between one linked machine and another. The machine that initiates the connection is called the client and the machine that it is linked to is called the server.primary partitionThe first division of a hard drive. Due to a limit on the size of the partition table, the maximum number of primary partitions that can be created on a hard disk is four.print jobAn item sent for printing, such as a file, together with the associated instructions to the printer that can be stored in a print queue before actually being printed.print queuePrint jobs are stored sequentially in a special buffer for each printer. The printer removes and prints the print job at the top of the queue until the queue is cleared.print spoolA file containing all of the documents that are waiting to be printed.printerIn Linux, a device that prints the characters onto the page.printer filterA program that changes the data in a file before it is printed.priorityA value that defines the level of detail to be maintained in the log file.priority numberA number that describes how important a process is and determines how much CPU time will be allocated to it.processA single program that is executed within its own virtual address space.process identifierSee PID.profileA file that contains the environmental preferences and access rights of a user.protocolA set of agreed rules governing a standard activity, for example the TCP/IP and PPP protocols which allow different computers to communicate.psA command that searches the /proc filesystem to display information about processes.pstreeA command that uses a tree structure to display all of the processes and the relationships between parent and child processes. See also child process, parent process.pwconvA command that enables shadowing.pwdA command that displays the name of the present working directory on the terminal screen.pwunconvA command that removes shadowing.Back to topQ

queueAn ordered list of jobs waiting to be printed.quotaThe amount of disk space in a partition that is made available to a group or user.Back to topR

RAM diskA disk drive simulated in memory.read/write headThe mechanism that allows data to be written to or read from a magnetic storage medium, such as a hard disk or a tape. In hard disks, each platter has a read/write head for each side.realnameThe name of a file containing library code. The realname consists of the soname plus the minor version number and, optionally, a release number.recursive commandA command that is executed in all subdirectories of a directory, instead of just the current directory, as is more usual.Red HatA widely used distribution of Linux that has pioneered package management with its RPM.Red Hat Package ManagerSee RPM.redirectionA process that allows the output of a command to be sent to a location other than its default location.regular expressionA type of character string, conforming to a particular syntax that is used to expand the parameters in pattern-matching searches. It does this by including special characters that function as wildcards. For example, enclosing a search string in square bracket symbols makes the search engine match any one of the characters in the enclosed string.Remote Procedure CallsSee RPC.reniceA command that lets the user change the priority of a process by altering the nice number.repquotaA command that analyzes and reports on each user's use of their quota.reserveA directive that allows users to pass an I/O address into the kernel. This prevents that memory address from being probed for a device by making the kernel think one has already been found.RFC 931A connection-based authentication server protocol for TCP networks that provides a mechanism by which a text string identifying the owner of a specified TCP connection can be returned to a server requesting that information.rmdirA command used to remove empty directories.rmmodA command for managing modules that allows the user to remove modules that are currently unused.root1. A term used to describe the top directory in a filesystem.2. The superuser or system administrator account. A person logged in under this account has unrestricted access to the system.rotateA process that involves closing and renaming a log file while immediately creating another, so that the files stay at a manageable size but the details of the process aren't lost.routing tableA table that contains information that determines the path or route that a packet is sent.RPCAn abbreviation for Remote Procedure Calls, requests issued by a client machine that invoke one of a range of services offered on a remote server machine.RPMAbbreviation for Red Hat Package Manager, a manager that assists with the tasks of building, installing, upgrading, uninstalling, verifying, and querying Linux packages. It maintains a database of all packages installed on a Linux system.RSA cryptographyA popular public-key cryptography system developed by Ronald Rivest, Adi Shamir, and Leonard Adleman in 1997.runSee execute.runlevelA variable that determines the running state of the operating system and so determines which sets of services are available. A definition in the inittab file determines the default runlevel for the system.Back to topS

SambaA system of tools that allows Linux to implement the SMB protocol.schedulerAn element of the kernel that manages the access of processes to the CPU.SCSIAcronym for small computer systems interface, a set of standard electronic interfaces that allows operating systems to communicate with up to 16 peripheral devices. All devices are connected by cable and controlled by a SCSI host adapter.sectorThe smallest unit of a hard disk that the operating system can access. Hard disk storage space is divided into concentric circles called tracks. Each track contains many sectors.Secure ShellSee ssh.securityApproaches that minimize the risk of data compromise. Restrictions may affect users, hosts, or network ports.sedA command that allows a set of text editing instructions to be created and applied to a file in one step.sendmailAn SMTP-based MTA, developed by Eric Allman, responsible for transferring e-mail. It also functions as a daemon, queues undeliverable messages, intercepts aliases, and rewrites addresses. Sendmail's operation is reliant on its main configuration file sendmail.cf.Server Message BlockSee SMB.setA command that delivers a list of environment variables and their values in the form name=value.set group IDSee SGID.set user IDSee SUID.SGIDAbbreviation for set group ID, a permission bit in a UNIX or Linux program that, when set, enables the program to run with group permissions, even if the person running the program is not a member of that group.shadowA password-protection system that stores passwords in a more secure location than the /etc/passwd file.shadow passwordAn encrypted password that is not stored in the /etc/passwd file. Instead, it is held in a shadow file that is not world-readable.shared librariesA collection of functions that is stored on the system and can be used by any program.sharewareA type of software that is available for trial use before purchase. Ongoing use of shareware must be paid for. It is often distributed as a limited version with some features disabled, or only operating for a trial period. See also freeware.shellA program that uses a command line as an interface between a user and an operating system.shell scriptA type of executable file that contains multiple shell commands. Scripts allow the sequence of commands to be invoked when the name of the script is entered at the command prompt.shutdownA command that is used to shut down safely. It stops any new users from logging on and sends a message to all the users on the system that the system is shutting down.Simple Mail Transfer ProtocolSee SMTP.Simple Network Management ProtocolSee SNMP.SLIPAcronym for Serial Line Internet Protocol, a dial-in protocol.slocateA command that is more secure version of the locate command. Its database stores permission information, so that users can list only the files they have legitimate access to.small computer systems interfaceSee SCSI.smart hostIn Linux and UNIX systems, a central mail-processing server used by the sendmail mail transfer agent. Client machines rely on this server to deliver messages to hosts at remote sites. Mail coming from this gateway appears to originate from a single host, rather than from multiple clients.SMBAbbreviation for Server Message Block, a protocol used by operating systems to share resources.smbdA daemon that handles notifications between the Samba server and the network, and manages authentication and data sharing. It must be running to use Samba. See also nmdb.SMTPAbbreviation for Simple Mail Transfer Protocol, a protocol for transporting messages over the Internet. It listens at port 25 and the initial transfer occurs between the e-mail client and e-mail server(s). SMTP relies on another protocol to retrieve messages from the server.sndconfigA configuration utility that is used for sound cards. It finds and autoconfigures all installed PCI and ISA plug-and-play sound cards that are installed on a system.SNMPAbbreviation for Simple Network Management Protocol a communication protocol that allows remote management of networked devices.socketsSockets are pieces of software used for communication between applications and network protocols in a TCP/IP network. Sockets are created and used with the sockets' API.soft limitThe maximum amount of disk space that a user is supposed to use. The hard limit represents the actual maximum available, but once the soft limit is passed, the user will be told to reduce the space they use.sonameA library filename used to determine compatibility between different versions of the library. When programs list the shared libraries that they need, they use the soname.sortA command that arranges the lines of text in a file according to the text's ASCII value.sound cardA peripheral device that attaches to a slot on a motherboard and allows the computer to receive, process, and output sounds.splitA command that splits a file by line or byte count.spoolerA program for placing printing jobs in a queue and removing them. Some spoolers provide facilities for managing the queue, including the order of jobs.ssh1. An abbreviation for Secure Shell, an application that allows users to execute commands on a remote machine across an untrusted network. 2. A protocol that runs on the application layer of the TCP/IP stack.stackA data structure where items are removed in the reverse order to which they were added.stack spaceThe area of memory taken up by the stack.standard errorAbbreviated to stderr, a data stream that collects error messages from all processes. These messages can be sent to a file or other output, but the default output is the video display. Standard error is usually file descriptor 2.standard inputAbbreviated to stdin, a data stream that sends data to all processes. The default data source is the keyboard, but another source such as a file can be used instead. Standard input is usually file descriptor 0.standard outputAbbreviated to stdout, a data stream that collects output from all processes. This output can be sent to a file or other output, but the default output is the video display. Standard output is usually file descriptor 1.startxA script file that executes the xinit command.static fileA file that contains data that doesn't change without system administrator intervention. Examples of static files include system configuration files, libraries, and binary files.statically linked programA program that's compiled to have its own copy of library routines.status lineIn vi, the line at the bottom of the screen that vi uses to display vi commands, error messages, and other status messages as editing progresses.stderrSee standard error.stdinSee standard input.stdoutSee standard output.sticky bitAn enhanced security bit that allows file owners to give ordinary users full read or write access to their directories, but prevents them from removing or renaming files within those directories.streamA data-transfer connection between an application and a device.suA command that allows a user to access the root account or other user accounts from the user's current account.subnetA discrete part of a network. On TCP/IP networks, the IP address of a node on a common subnet has the same prefix as the IP addresses of other nodes on the subnet.subnet maskA type of IP address used to determine what subnet an address belongs to.subnettingA term that describes the division of the host part of an IP address, as defined by the default network mask, into two or more subnets.SUIDAn acronym for set user ID, a permission bit in a UNIX or Linux program that, when set, enables the program to run with the owner's permissions regardless of who is actually running it.SUID/SGID auditA system-wide sweep to check for instances of SUID or SGID permissions that may be used by unauthorized users to gain root access.superdaemonA program that monitors the other daemons.SuperProbeA utility, available under most Linux distributions, that attempts to determine the video card's chipset.superuserAn account that provides unlimited access to all files and commands on the system.SuSEA version of Linux that targets users who need an entry-level introduction to Linux.SVGAAbbreviation for Super Video Graphics Array, a range of graphics display standards that were established by VESA (Video Electronics Standards Association). It supports a palette of up to 16 million colours, though the actual number of displayed colours is limited by the amount of available video memory. SVGA offers a maximum resolution of 1600 by 1200 pixels. The minimum display quality defined by SVGA is 256 colours at 800 by 600 pixels.swap spaceThe area on a hard disk, either in the form of a swap file or a dedicated partition, that enables the loaded applications and data to exceed the capacity of the physical RAM. The process involves swapping temporarily inactive portions of code, known as pages or segments, from the main memory to the hard drive.swappingThe process that copies pages containing addresses into main memory. See also swap space.symlinkA type of link that exists between files that have each have a different inode but all refer to a single original file.syslogdA command that activates or instructs the syslog daemon.system commandsTypes of program that are run by typing the command name.system logA log that contains a record of system activity.Back to topT

tacA command that prints a file in reverse file order.tailA command that displays the end of a file.taperAn archive utility that has a text-based interface.tarThe most common method of packaging source code. Using options, tar can also be used to work with archives without the need for gunzip.tarballA software package consisting of a compressed tar archive. The file extensions for tarballs are .tar.gz or .tgz. See also tarfile.tarfileA single file containing the entire directory tree structure for a downloaded, open source software project.TCPAcronym for Transmission Control Protocol, a communication standard that works in conjunction with the Internet Protocol to connect hosts on the Internet and transmit data over networks. It is connection-oriented and is the de facto Internet protocol.TCP WrappersIn UNIX and Linux, programs that provide access control for service daemons by monitoring and filtering incoming network service requests. Optional features provided by this network security tool include logging, client username lookups with the RFC 931 protocol, and protection against hostname and IP address spoofing.TCP/IPAbbreviation for Transmission Control Protocol/ Internet Protocol, the suite of communications protocols used to connect computers on the Internet.teeA redirection process that sends the output of a command to another location, while continuing to display it at the default location.teletype terminalAn early communications terminal, manufactured by the Teletype Corporation.telnetA program used to access machines remotely.TerabyteA unit of computer data storage capacity equivalent to a thousand gigabytes.testA command that is commonly used in Linux shell scripts to check the properties of integers, command output, and files. It is commonly used as an argument in an if statement. It compares values and tests the status of files.testparmA utility that helps check Samba configuration files to ensure that the file is internally correct.text editorA program that allows users to manipulate text files. Common examples in Linux include vi, emacs, and pico.text streamA line of single characters that displays on screen.themeA collection of settings that create a unified desktop environment, including appearances and features.threadSee process.timesharingA method by which all active processes share the CPU between them rather than waiting for each process to finish before the next one starts.topA command that shows which processes are using the most CPU time.touchA command that changes the data attributes of a file.tracerouteA utility that traces the route a packet travels from the user's computer and over the Internet to specified destination.trapAsynchronous information sent from an SNMP agent to an NMS.Trojan horseA damaging program that is disguised as an ordinary application.Back to topU

UARTAbbreviation for Universal Asynchronous Receiver/Transmitter, the chip that controls a computer's interface with its attached serial devices.UDPAbbreviation for User Datagram Protocol, the main connectionless protocol that is used within the TCP/IP suite. Because UDP does not send and receive data packets in a sequential manner, it is generally used to send small units of data that require little reassembling.UIDAbbreviation for user identification number, a number Linux uses to track users.ulimitA command that places limits on the resources that the Bash shell and its users can access.umaskA filter that determines which permission bits will not be set on file creation.umountA command that is used to unmount filesystems after use.Universal Asynchronous Receiver/TransmitterSee UART.UNIXA multiuser, multitasking operating system developed in the early 1970s and written completely in the C language. Linux is derived from UNIX.unmountA command used to remove a device from the filesystem.unsetA command that removes a variable or function from the shell.untilA loop command that executes specified code as long as the condition specified in the command returns a false or not zero return. It is the negative form of the while command. See also for command.updatedbA command that updates the slocate database.UPSAbbreviation for uninterruptible power supply, a hardware device used to protect sensitive computers from fluctuations and interruptions in the power supply.upstreamA term that indicates the direction of data. Data is described as moving from the application to the output device, so upstream is in the direction of the application.User Datagram ProtocolSee UDP.user spaceThe area of the Linux architecture that runs user programs and with which the user will interact, as opposed to the kernel space, which handles the low-level processes.useraddA command that adds new user accounts to the Linux system.userdelA command that deletes user accounts from the Linux system.usermodA command that modifies user accounts to the Linux system.usrquotaA command that defines how much disk space will be made available to a user.Back to topV

variableA symbolic entity that is used to represent a value. In programming, variables are used to avoid having to hard-code values and to allow the same code to be run using different values without needing to modify the code itself.vertical refresh rateAlso known as the vertical scan rate, or frame rate, a measure of the maximum number of frames that can be displayed on a monitor in a second, expressed in Hertz (Hz).VGAAbbreviation for Video Graphics Array, the minimum standard for PC video display. On most monitors, VGA's 640x480 pixel resolution has been upgraded to the SuperVGA standard.viA program used to edit text.vimAbbreviation for vi improved, an improved version of the Linux vi editor.virtual memoryMemory that is created by swap space. Temporarily inactive portions of code are stored in virtual memory in the swap space to increase RAM capacity.vlockA utility that allows you to lock access to a session or sessions on a computer running Linux. This provides the capability to allow multiple users access without compromising the security of other sessions.Back to topW

wcA command that displays the number of words, lines, or characters in a file.whatisA command that is used to get a short description of a command's function.whereisA command that is used to discover a command's location, if the command being searched exists on the command path.whichA command that searches for a program in the directories defined by the PATH environment variable.whileA loop command that continuously executes specified code as long as the condition specified in the command is met. See also until and for commands.whoA command that displays a listing of all the users logged into the Linux system.wildcardA special symbol that stands for any character, used by an operating system as a means of identifying and processing multiple files. Wildcards are also used by many text editors to help identify text strings. See regular expression.windowAn area of the screen that displays a particular application program.window managerA client program that controls how windows in the X Window System are presented to users and enables users to interact with them. It also manages other client programs.WinmodemA software-based modem developed for the Microsoft Windows operating system that uses the motherboard chipset rather than electronics on the modem itself to carry out much of the modem's hardware functions.Back to topX

XIn UNIX, Linux, and other UNIX-like systems, a widely used contraction for X Window System.X clientIn Linux, any application that sends valid requests to create a window for instance, or display an image to an X server. X clients are network-transparent it doesn't matter if they run on local or remote machines.X consortiumA group of software producers that maintain the standards for and issue releases of the X Window System.X Display ManagerSee xdm.X font serverAbbreviated to xfs, a service that provides a mechanism for an X server to communicate with a font renderer, usually running on a remote machine.X protocolA language used by X servers and X clients for communication.X serverSoftware in the X Window System or XFree86 for UNIX, Linux, and other UNIX-like systems that runs on the local machine and manages a single screen, keyboard, and mouse. The X server is responsible for displaying drawing requests initiated by the X client on the local screen.X Window SystemCommonly abbreviated to X, a hardware-independent graphical windowing environment for UNIX and Linux.X11A version of the X Window System, which is one of the major UNIX standards.xargsA command substitution process that takes the output of a number of programs or commands and connects them with a pipe to the input of another. It's commonly used to carry out the same command on a series of files.xconfigA graphical program that supplies help and extra information on a multitude of options. It uses the X Windowing System.XconfiguratorIn the Red Hat distribution of Linux, a graphical utility used to configure the X Window System. It offers a series of menu options chosen via the keyboard.xdmAcronym for X Display Manager, the program that is responsible for organizing the display area and painting graphics in the X Window System.XF86ConfigThe configuration file that contains all the information required to configure XFree86 correctly. It's an ASCII text file, divided into 12 sections, some of which are optional.XF86SetupA graphical utility for Linux with buttons, radio buttons, and sliders, used to configure XFree86. It's available with popular distributions such as Caldera and Debian, but is not distributed with Red Hat.XFree86A freely distributable port of the X Window System Release 6, Version 11 for Intel-based chips. XFree86 enables graphical applications to run on PCs using Linux, and can be thought of as the framework on which all the graphical user interfaces (GUIs) stand.xfsSee X font server.xinitThe command used to start X Window System.xlockA utility that locks the x display and requires the user to enter a password or the root password for re-entry. When it's running, all new server connections are refused.xmanA GUI utility used to display information about system commands.Back to topY

Z

zombieA dead process that can't be killed in the normal way.Back to top#

&A special symbol that is added to the end of a command and means that the command will be run in the background..A special symbol that stands for the current directory...A special symbol that stands for the parent directory of the current directory./binA directory used to store user commands./etc/fstabA file used to store information about the devices and filesystems used by Linux. The information in /etc/fstab is used at boot time and whenever listed filesystems are mounted. See also device and filesystem./sbinA directory used to store system administration commands./usr/binA directory used to store user commands.\A special symbol that indicates a command is continuing onto a second line.^oldtext^newtextA command that recalls the last entered command and substitutes the old text with new text.Back to top

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z #Copyright 2004 SkillSoft PLC. All rights reserved.SkillSoft and the SkillSoft logo are trademarks or registered trademarksof SkillSoft PLC in the United States and certain other countries.All other logos or trademarks are the property of their respective owners.