A device file that is used to communicate with a block oriented I/O device. Disk and tape drives are examples of block devices. The block-special file refers to the entire device. You should not use this file unless you want to ignore the directory structure of the device (that is, if you are coding a device driver). boot or boot up The process of starting the operating system (UNIX). Bourne Shell The original standard user interface to UNIX that supported limited programming capability. BSD UNIX Version of UNIX developed by Berkeley Software Distribution and written at UC Berkeley buffer (vi) The working version of the file you are editing is usually called the buffer; the buffer is actually an image of the file kept in random access memory during editing; changes are made in this image and only written out to disk upon user command (or when the vi autowrite setting is in effect); see also named buffer and undo buffer. buffer list (emacs) A special window which shows all of the buffers currently open; allows you to manipulate buffers using buffer list commands. C Programming language developed by Brian W. Kernighan and Dennis M. Ritchie. The C language is highly portable and available on many platforms including mainframes, PCs, and, of course, UNIX systems. C Shell A user interface for UNIX written by Bill Joy at Berkeley. It also features C programming-like syntax. CD-ROM (Compact Disk-Read Only Memory) Computer-readable data stored on the same physical form as a musical CD. Large capacity, inexpensive, slower than a hard disk, and limited to reading. There are versions that are writable (CD-R, CD Recordable) and other formats that can be written to once or many times. CGI (Common Gateway Interface) A means of transmitting data between Web pages and programs or scripts executing on the server. Those programs can then process the data and send the results back to the users browser through dynamically creating HTML. character-special A device file that is used to communicate with character-oriented I/O devices such as terminals, printers, or network communications lines. All I/O access is treated as a series of bytes (characters). characters 1. alphabetic The letters A through Z and a through z. 2. alphanumeric The letters A through Z and a through z, and the numbers 0 through 9. 3. control Any non-printable characters. The characters are used to control devices, separate records, and eject pages on printers. 4. numeric The numbers 0 through 9. 5. special Any of the punctuation characters or printable characters that are not alphanumeric. Include the space, comma, period, and many others. child-process See sub-process. child-shell See sub-shell. class A model of objects that have attributes (data) and behavior (code or functions). It is also viewed as a collection of objects in their abstracted form. command line (1) The shell command line from which the current vi or Emacs session was started; (2) the ex command line, where ex commands are entered. command line editing UNIX shells support the ability to recall a previously entered command, modify it, and then execute the new version. The command history can remain between sessions (the commands you did yesterday can be available for you when you log in today). Some shells support a command line editing mode that uses a subset of the vi, emacs, or gmacs editor commands for command recall and modification. command line history See command line editing. command line parameters Used to specify parameters to pass to the execute program or procedure. Also known as command line arguments. command prompt See shell prompt. completion (emacs) The automatic provision of the rest of a command or a file name; when the command or file name cannot be resolved to a single entity, a menu of choices is provided (type a few characters of the name and press TAB; Emacs will either complete the name or give you a menu of choices). configuration files Collections of information used to initialize and set up the environment for specific commands and programs. Shell configuration files set up the user's environment. configuration files, shell For Bourne shell: /etc/profile and $HOME/.profile. For Korn shell: /etc/profile, $HOME/.profile, and ENV= file. For C shell: /etc/.login, /etc/cshrc, $HOME/.login, $HOME/.cshrc, and $HOME/.logout. Older versions may not support the first two files listed. For BASH: /etc/profile/, $HOME/.bash_profile, $HOME/.bash_login, $HOME/.profile, $HOME/.bashrc, ~/.bash_logout. control keys These are keys that cause some function to be performed instead of displaying a character. These functions have names, for instance, the end-of-file key tells the UNIX that there is no more input. The typical end-of-file key is the <^D> (control-d) key. CPU (Central Processing Unit) The primary "brain" of the computer; the calculation engine and logic controller. current macro (emacs) The most recently recorded macro; it is executed by the call-last-kbd-macro function. cursor The specific point on the screen where the next editing action will take place; the cursor is usually indicated on the screen by some sort of highlighting, such as a underscore or a solid block, which may or may not be blinking. daemon A system related background process that often runs with the permissions of root and services requests from other processes. DARPA (U.S. Department of Defense Advanced Research Projects Agency) Funded development of TCP/IP and ARPAnet (predecessor of the Internet). database server See server, database. default settings Most tools and systems are governed by a number of settings; those that are in effect when the tool is started is known as the default. vi is governed by a number of settings; the default settings are those in effect when vi is first started and no automatic overrides of settings are in effect through .exrc files or EXINIT environment variables. device file File used to implement access to a physical device. This provides a consistent approach to access of storage media under UNIX data files and devices (such as tapes and communication facilities) are implemented as files. To the programmer, there is no real difference. directory A means of organizing and collecting files together. The directory itself is a file that consists of a list of files contained within it. The root (/) directory is the top level and every other directory is contained in it (directly or indirectly). A directory might contain other directories, which are known as sub-directories. directory navigation The process of moving through directories is known as navigation. Your current directory is known as the current working directory. Your login directory is known as the default or home directory. Using the cd command, you can move up and down through the tree structure of directories. DNS (Domain Name Server) Used to convert the name of a machine on the Internet (name.domain.com) to the numeric address (123.45.111.123). DOS (Disk Operating System) Operating system that is based on the use of disks for the storage of commands. It is also a generic name for MS-DOS and PC-DOS on the Personal Computer. MS-DOS is the version Microsoft sells and PC-DOS is the version IBM sells. Both are based on Microsoft code. EBCDIC (Extended Binary Coded Decimal Interchange Code) The code used to represent characters in memory for mainframe computers. echo The display on the screen of characters you type is sometimes called the echo of characters; it is called this because usually your terminal is set up not to display the characters directly as typed, but rather to wait for them to be sent to the computer, which then echoes (sends) them back to your terminal. ed A common tool used for line-oriented text editing. e-mail Messages sent through an electronic medium instead of through the local postal service. There are many proprietary e-mail systems that are designed to handle mail within a LAN environment; most of these are also able to send over the Internet. Most Internet (open) e-mail systems make use of MIME to handle attached data (which can be binary). emacs A freely available editor now part of the GNU software distribution. Originally written by Richard M. Stallman at MIT in the late 1970's, it is available for many platforms. It is extremely extensible and has its own programming language; the name stands for Editing with MACroS.encapsulation. The process of combining data (attributes) and functions (behavior in the form of code) into an object. The data and functions are closely coupled within an object. Instead of every programmer being able to access the data in a structure his own way, programmers have to use the code connected with that data. This promotes code reuse and standardized methods of working with the data. environment variables See variables, environmental. escape (1) (vi) The Esc key, used to terminate insert mode, or an incomplete vi command; (2) To prevent a character from having its normal interpretation by a program by preceding it with the escape character (usually \, the backslash); for example in a regular expression, to search for a literal character that has a special meaning in a regular expression, it must be escaped; as a specific example, to search for a period (.), you must type it escaped as \. ethernet A networking method where the systems are connected to a single shared bus and all traffic is available to every machine. The data packets contain an identifier of the recipient, which is the only machine that should process that packet. expression A constant, variable, or operands and operators combined. Used to set a value, perform a calculation, or set the pattern for a comparison (regular expressions). fifo First In, First Out. See named pipe. file Collection of bytes stored on a device (typically a disk or tape). Can be source code, executable binaries or scripts, or data. 1. indexed A file based on a file structure where data can be retrieved based on specific keys (name, employee number, and so on) or sequentially. The keys are stored in an index. This is not directly supported by the UNIX operating system; usually implemented by the programmer or by using tools from an ISV. A typical form is known as ISAM. 2. line sequential See file, text. 3. sequential a. A file that can only be accessed sequentially (not randomly). b. A file without record separators. Typically fixed length but UNIX does not know what that length is and does not care. 4. text A file with record separators. May be fixed or variable length; UNIX tools can handle these files because it can tell when the record ends (by the separator). file compression The process of applying mathematical formula to data typically resulting in a form of the data that occupies less space. A compressed file can be uncompressed (lossless) resulting in the original file. When the compression/uncompress process results in exactly the same file as was originally compressed, it is known as lossless. If information about the original file is lost, the compression method is know as lossy. Data and programs need lossless compression; images and sounds can stand lossy compression. filename The name used to identify a collection of data (a file). Without a pathname, it is assumed to be in the current directory. filename generation The process of the shell interpreting meta-characters (wild cards) to produce a list of matching files. This is referred to as filename expansion or globbing. filename, fully qualified The name used to identify a collection of data (a file) and its location. It includes both the path and name of the file; typically, the pathname is fully specified (absolute). See also pathname and pathname, absolute. filesystem A collection of disk storage that is connected (mounted) to the directory structure at some point (sometimes at the root). Filesystems are stored in a disk partition and are also referred to as disk partitions. firewall A system used to provide a controlled entry point to the internal network from the outside (usually the Internet). This is used to prevent outside or unauthorized systems from accessing systems on your internal network. The capability depends on the individual software package, but the features typically include: filter packets, filter datagrams, provide system (name or IP address) aliasing, and rejecting packets from certain IP addresses. It can also prevent internal systems from accessing the Internet on the outside. In theory, it provides protection from malicious programs or people on the outside. The name comes from the physical barrier between connected buildings or within a single building that is supposed to prevent fire from spreading from one to another. flags See options. foreground Programs running while connected to the interactive session. fseek Internal function used by UNIX to locate data inside a file or filesystem. ANSI standard fseek accepts a parameter that can hold a value of +2 to -2 billion. This function, used by the operating system, system tools, and application programs, is the cause of the 2 GB file and filesystem size limitation on most systems. With 64 bit operating systems, this limit is going away. FTP (File Transfer Protocol, or File Transfer Program) A system-independent means of transferring files between systems connected via TCP/IP. Ensures that the file is transferred correctly, even if there are errors during transmission. Can usually handle character set conversions (ASCII/EBCDIC) and record terminator resolution (<lf> for UNIX, <cr> and <lf> for MS/PC-DOS). gateway A combination of hardware, software, and network connections that provides a link between one architecture and another. Typically, a gateway is used to connect a LAN or UNIX server with a mainframe (that uses SNA for networking resulting in the name: SNA gateway). A gateway can also be the connection between the internal and external network (often referred to as a firewall). See also firewall. globbing See filename generation. GNU GNU stands for GNU's Not Unix, and is the name of free useful software packages commonly found in UNIX environments that are being distributed by the GNU project at MIT, largely through the efforts of Richard Stallman. grep A common tool used to search a file for a pattern. egrep and fgrep are newer versions. Egrep allows the use of extended (hence the "e" prefix) regular expressions, fgrep uses limited expressions for a faster (hence the "f" prefix) searches. here document The << redirection operator, known as here document, allows keyboard input (stdin) for the program to be included in the script. HTML (HyperText Markup Language) Describes World Wide Web pages. It is the document language that is used to define the pages available on the Internet through the use of tags. A browser interprets the HTML to display the desired information. i-node Used to describes a file and its storage. The directory contains a cross reference between the i-node and pathname/filename combination. Also known as inode. I-Phone (Internet Phone) A method of transmitting speech long distances over the Internet in near real-time allowing the participants to avoid paying long distance telephone charges. They still pay for the call to their ISP and the ISP's service charges. ICMP (Internet Control Message Protocol) Part of TCP/IP that provides network layer management and control. inheritance A method of object-oriented software reuse in which new classes are developed based on existing ones by using the existing attributes and behavior and adding on to them. For example, if the base object is automobile with attributes of an engine, four wheels, and tires, and behavior of acceleration, turning, and deceleration, then a sports car would modify the attributes so the engine would be larger or have more horsepower than the default, the four wheels would include alloy wheels and high speed rated tires, and the behavior would also be modified for faster acceleration, tighter turning radius, and faster deceleration. inode See i-node. Internet A collection of different networks that provide the ability to move data between them. It is built on the TCP/IP communications protocol. Originally developed by DARPA, it was taken over by NSF, and has now been released from governmental control. Internet Service Provider The people who connect you to the Internet. IRC (Internet Relay Chat) A server-based application that allows groups of people to communicate simultaneously through text-based conversations. IRC is similar to Citizen Band radio or the "chat rooms" on some bulletin boards. Some chats can be private (between invited people only) or public (where anyone can join in). IRC now also supports sound files as well as text it can also be useful for file exchange. ISAM (Indexed Sequential Access Method) On UNIX and other systems, ISAM refers to a method for accessing data in a keyed or sequential way. The UNIX operating system does not directly support ISAM files; they are typically add on products. ISP See Internet Service Provider. ISV (Independent Software Vendor) Generic name for software vendors other than your hardware vendor. kernel The core of the operating system that handles tasks such as memory allocation, device input and output, process allocation, security, and user access. UNIX tends to have a small kernel when compared to other operating systems. keyboard macros A feature which allows a special key sequence to stand for another, usually more complex sequence; in vi, keyboard macros are implemented via the :map command. kill ring (emacs) A set of buffers where killed text is kept; the buffers are arranged in a circular pattern. When commands that automatically move from one buffer to the next get to the end of the set, the next movement will be to the first buffer in the ring. Korn Shell A user interface for UNIX with extensive scripting (programming) support. Written by David G. Korn. The shell features command line editing and will also accept scripts written for the Bourne Shell. LAN (Local Area Network) A collection of networking hardware, software, desktop computers, servers, and hosts all connected together within a defined local area. A LAN could be an entire college campus. limits See quota. line address (vi and ex) The way a selected set of lines is indicated in ex mode is through a line address. A line address can be an absolute line number, relative line number, or special symbols which refer to the beginning or of the file. link 1. hard Directory entry that provides an alias to another file that is in the same filesystem. Multiple entries appear in the directory (or other directories) for one physical file without replication of the contents. 2. soft See symbolic link. 3. symbolic Directory entry that provides an alias to another file that can be in another filesystem. Multiple entries appear in the directory for one physical file without replication of the contents. Implemented through link files; see also link file. 4. file File used to implement a symbolic link producing an alias on one filesystem for a file on another. The file only contains the fully qualified filename of the original (linked-to) file. [...]... component Used for security and performance reasons super-user See root system administrator The person who takes care of the operating system and user administrative issues on UNIX systems Also called a system manager although that term is much more common in DEC VAX installations system manager See system administrator system programmer See system administrator TCP/IP (Transport Control Protocol/Internet... page to another through the use of URLs (Uniform Resource Locators) WWW See World Wide Web X Window System A windowing and graphics system developed by MIT, to be used in client/server environments X See X Window System X11 See X Window System X-windows The wrong term for the X Window System See X Window System ©Copyright, Macmillan Computer Publishing All rights reserved ©Copyright, Macmillan Computer... but the compiler keeps track and figures it all out) POSIX POSIX stands for "Portable Operating System Interface, UNIX" It is the name for a family of open system standards based on UNIX The name has been credited to Richard Stallman The POSIX Shell and Utilities standard developed by IEEE Working Group 100 3.2 (POSIX.2) concentrates on the command interpreter interface and utility programs PPP (Point-to-Point... program under UNIX The user's interactive session is a process A process can invoke (run) and control another program that is then referred to as a sub-process Ultimately, everything a user does is a subprocess of the operating system process identifier Shown in the heading of the ps command as PID The unique number assigned to every process running in the system quota General description of a system- imposed... connect systems to the ARPANET tcsh A C shell-like user interface featuring command-line editing Telnet Protocol for interactive (character user interface) terminal access to remote systems The terminal emulator that uses the telnet protocol is often known as telnet or tnvt100 Terminal A hardware device, normally containing a cathode ray tube (screen) and keyboard for human interaction with a computer system. .. subroutines that run on a remote system from the local one scripts A program written for a UNIX utility including shells, AWK, perl, sed, and others Also see shell scripts sed A common tool used for stream text editing, having ed-like syntax server, database A system designated to run database software (typically a relational database like Oracle, SQL Server, Sybase, or others) Other systems connect to this... in combination with a user id to gain access to a UNIX system pathname The means used to represent the location of a file in the directory structure If you do not specify a pathname, it defaults to the current directory Also see absolute pathname and relative pathname PDP (Personal Data Processor) Computers manufactured by Digital Equipment Corporation UNIX was originally written for a PDP-7 and gained... "owner." Most are not and the title of the group is no guarantee that the discussion will be related The "official" term for this is Usenet News NFS (Network File System) Means of connecting disks that are mounted to a remote system to the local system as if they were physically connected NIS (Network Information Service) A service that provides information necessary to all machines on a network, such... status flags on a file that tells UNIX to load a copy of the file into the page file the first time it is executed This is done for programs that are commonly used so the bytes are available quickly When the sticky bit is used on frequently used directories, they are cached in memory stream A sequential collection of data All files are streams to the UNIX operating system To it, there is no structure... actions take place Shell The part of UNIX that handles user input and invokes other programs to run commands Includes a programming language See also Bourne Shell, C Shell, Korn Shell, tcsh, and BASH shell environment The shell program (Bourne, Korn, C, tcsh, or BASH), invocation options, and preset variables that define the characteristics, features and functionality of the UNIX command line and program . of starting the operating system (UNIX) . Bourne Shell The original standard user interface to UNIX that supported limited programming capability. BSD UNIX Version of UNIX developed by Berkeley. reasons. super-user See root. system administrator The person who takes care of the operating system and user administrative issues on UNIX systems. Also called a system manager although that. 2 GB file and filesystem size limitation on most systems. With 64 bit operating systems, this limit is going away. FTP (File Transfer Protocol, or File Transfer Program) A system- independent