glossary.html

linux-unix130.linux.and.unix.ebooks130 linux and unix ebookslinuxLearning Linux - Collection of 12 E

<DT><B><TT>RCS</TT>
</B>
<DD>Revision Control System.
<DT><B><TT>redirection</TT>
</B>
<DD>The process of directing a data flow from the default. Input can be redirected to get data from a file or the output of another program. Normal output can be sent to another program or a file. Errors can be sent to another program or a file.
<DT><B><TT>regular expression</TT>
</B>
<DD>A way of specifying and matching strings for shells (filename wildcarding), <TT>grep</TT> (file searches), <TT>sed</TT>, and <TT>awk</TT>.
<DT><B><TT>reserved word</TT>
</B>
<DD>A set of characters that are recognized by UNIX and related to a specific program, function, or command.
<DT><B><TT>RFC</TT>
</B>
<DD>Request For Comment Document used for creation of Internet- and TCP/IP-related standards.
<DT><B><TT>rlogin</TT>
</B>
<DD>Remote Login. Gives the same functionality as <TT>telnet</TT>, with the added functionality of not requiring a password from trusted clients, which can also create security concerns (see also <TT><I>telnet</I></TT>).
<DT><B><TT>root</TT>
</B>
<DD>The user that owns the operating system and controls the computer. The processes of the operating system run as though a user, root, signed on and started them. Root users are all- powerful and can do anything they want. For this reason, they are often referred to as superusers. Root is also the very top of the directory tree structure.
<DT><B><TT>routing</TT>
</B>
<DD>The process of moving network traffic between two different physical networks; also decides which path to take when there are multiple connections between the two machines. It might also send traffic around transmission interruptions.
<DT><B><TT>RPC</TT>
</B>
<DD>Remote Procedural Call. Provides the ability to call functions or subroutines that run on a remote system from the local one.
<DT><B><TT>RPM</TT>
</B>
<DD>Red Hat Package Manager.
<DT><B><TT>script</TT>
</B>
<DD>A program written for a UNIX utility including shells, <TT>awk</TT>, Perl, <TT>sed</TT>, and others. See also <TT>shell scripts</TT>.
<DT><B><TT>SCSI</TT>
</B>
<DD>Small Computer System Interface.
<DT><B><TT>sed</TT>
</B>
<DD>A common tool used for stream text editing, having <TT>ed</TT>-like syntax.
<DT><B><TT>server, database</TT>
</B>
<DD>A system designated to run database software (typically a relational database like Oracle, SQL Server, Sybase, or others). Other systems connect to this one to get the data (client applications).
<DT><B><TT>SGID</TT>
</B>
<DD>Set group ID.
<DT><B><TT>shell</TT>
</B>
<DD>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, <TT>tcsh</TT>, and <TT>bash</TT>.
<DT><B><TT>shell environment</TT>
</B>
<DD>The shell program (Bourne, Korn, C, <TT>tcsh</TT>, or <TT>bash</TT>), invocation options and preset variables that define the characteristics, features, and functionality of the UNIX command-line and program execution interface.
<DT><B><TT>shell or command prompt</TT>
</B>
<DD>The single character or set of characters that the UNIX shell displays for which a user can enter a command or set of commands.
<DT><B><TT>shell scripts</TT>
</B>
<DD>A program written using a shell programming language like those supported by Bourne, Korn, or C shells.
<DT><B><TT>signal</TT>
</B>
<DD>A special flag or interrupt that is used to communicate special events to programs by the operating system and other programs.
<DT><B><TT>SLIP</TT>
</B>
<DD>Serial Line Internet Protocol. Internet over a serial line (modem). The protocol frames and controls the transmission of TCP/IP packets of the line.
<DT><B><TT>SNA</TT>
</B>
<DD>System Network Architecture. IBM networking architecture.
<DT><B><TT>stderr</TT>
</B>
<DD>The normal error output for a program that is sent to the screen by default. Can be redirected to a file.
<DT><B><TT>stdin</TT>
</B>
<DD>The normal input for a program, taken from the keyboard by default. Can be redirected to get input from a file or the output of another program.
<DT><B><TT>stdout</TT>
</B>
<DD>The normal output for a program that is sent to the screen by default. Can be redirected to a file or to the input of another program.
<DT><B><TT>sticky bit</TT>
</B>
<DD>One of the 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, it is cached in memory.
<DT><B><TT>stream</TT>
</B>
<DD>A sequential collection of data. All files are streams to the UNIX operating system. To it, there is no structure to a file; that is something imposed by application programs or special tools (ISAM packages or relational databases).
<DT><B><TT>subdirectory</TT>
</B>
<DD>See <TT>directory</TT>.
<DT><B><TT>subnet</TT>
</B>
<DD>A portion of a network that shares a common IP address component. Used for security and performance reasons.
<DT><B><TT>subprocess</TT>
</B>
<DD>Process running under the control of another, often referred to as the parent process. See also <TT>process</TT>.
<DT><B><TT>subshell</TT>
</B>
<DD>Shell running under the control of another, often referred to as the parent shell (typically the login shell). See also <TT>shell</TT>.
<DT><B><TT>SUID</TT>
</B>
<DD>Set user ID.
<DT><B><TT>superuser</TT>
</B>
<DD>Usually the root operator.
<DT><B><TT>sysadmin</TT>
</B>
<DD>Burnt-out root operator (system administrator).
<DT><B><TT>system administrator</TT>
</B>
<DD>The person who takes care of the operating system and user administrative issues on UNIX systems. Also called a <TT>system manager</TT>, although that term is much more common in DEC VAX installations.
<DT><B><TT>system manager</TT>
</B>
<DD>See <TT>system administrator</TT>.
<DT><B><TT>system programmer</TT>
</B>
<DD>See <TT>system administrator</TT>.
<DT><B><TT>tar</TT>
</B>
<DD>Tape archiving utility.
<DT><B><TT>TCP</TT>
</B>
<DD>Transmission Control Protocol.
<DT><B><TT>TCP/IP</TT>
</B>
<DD>Transport Control Protocol/Internet Protocol. The pair of protocols and also generic name for suite of tools and protocols that forms the basis for the Internet. Originally developed to connect systems to the ARPAnet.
<DT><B><TT>tcsh</TT>
</B>
<DD>A C shell-like user interface featuring command-line editing.
<DT><B><TT>telnet</TT>
</B>
<DD>Remote login program.
<DT><B><TT>Telnet</TT>
</B>
<DD>Protocol for interactive (character user interface) terminal access to remote systems. The terminal emulator that uses the Telnet protocol is often known as <TT>telnet</TT> or <TT>tnvt100</TT>.
<DT><B><TT>termcap</TT>
</B>
<DD>Terminal capability database.
<DT><B><TT>terminal</TT>
</B>
<DD>A hardware device, normally containing a cathode ray tube (screen) and keyboard for human interaction with a computer system.
<DT><B><TT>text processing languages</TT>
</B>
<DD>A way of developing documents in text editors with embedded commands that handle formatting. The file is fed through a processor that executes the embedded commands, producing a formatted document. These include <TT>roff</TT>, <TT>nroff</TT>, <TT>troff</TT>, <TT>RUNOFF</TT>, TeX, LaTeX, and even the mainframe <TT>SCRIPT</TT>.
<DT><B><TT>TFTP</TT>
</B>
<DD>Trivial File Transfer Protocolor Trivial File Transfer Program. A system-independent means of transferring files between systems connected via TCP/IP. It is different from FTP in that it does not ensure that the file is transferred correctly, does not authenticate users, and is missing a lot of functionality (like the <TT>ls</TT> command).
<DT><B><TT>tin</TT>
</B>
<DD>Interactive news reader.
<DT><B><TT>top</TT>
</B>
<DD>A common tool used to display information about the top processes on the system.
<DT><B><TT>UDP</TT>
</B>
<DD>User Datagram Protocol. Part of TCP/IP used for control messages and data transmission where the delivery acknowledgment is not needed. The application program must ensure data transmission in this case.
<DT><B><TT>UID</TT>
</B>
<DD>User ID number.
<DT><B><TT>UIL</TT>
</B>
<DD>Motif User Interface Language.
<DT><B><TT>URL</TT>
</B>
<DD>Uniform Resource Locator. The method of specifying the protocol, format, login (usually omitted), and location of materials on the Internet.
<DT><B><TT>Usenet</TT>
</B>
<DD>See <TT>Netnews</TT>.
<DT><B><TT>UUCP</TT>
</B>
<DD>UNIX-to-UNIX copy program. Used to build an early, informal network for the transmission of files, email, and Netnews.
<DT><B><TT>variables, attributes</TT>
</B>
<DD>The modifiers that set the variable type. A variable can be string or integer, left- or right-justified, read-only or changeable, and other attributes.
<DT><B><TT>variables, environmental</TT>
</B>
<DD>A place to store data and values (strings and integers) in the area controlled by the shell so they are available to the current and subprocesses. They can just be local to the current shell or available to a subshell (exported).
<DT><B><TT>variables, substitution</TT>
</B>
<DD>The process of interpreting an environmental variable to get its value.
<DT><B><TT>WAN</TT>
</B>
<DD>Wide Area Network.
<DT><B><TT>Web</TT>
</B>
<DD>See <TT>World Wide Web</TT>.
<DT><B><TT>whitespace</TT>
</B>
<DD>Blanks, spaces, and tabs that are normally interpreted to delineate commands and filenames unless quoted.
<DT><B><TT>wildcard</TT>
</B>
<DD>Means of specifying filename(s) whereby the operating system determines some of the characters. Multiple files might match and will be available to the tool.
<DT><B><TT>World Wide Web</TT>
</B>
<DD>A collection of servers and services on the Internet that run software and communicate using a common protocol (HTTP). Instead of the users&#146; having to remember the location of these resources, links are provided from one Web page to another through the use of URLs.
<DT><B><TT>W W W</TT>
</B>
<DD>See <TT>World Wide Web</TT>.
<DT><B><TT>WYSIWYG</TT>
</B>
<DD>What You See Is What You Get.
<DT><B><TT>X</TT>
</B>
<DD>See <TT>X Window System</TT>.
<DT><B><TT>X Window System</TT>
</B>
<DD>A windowing and graphics system developed by MIT, to be used in client/server environments.
<DT><B><TT>X11</TT>
</B>
<DD>See <TT>X Window System</TT>.
<DT><B><TT>X-windows</TT>
</B>
<DD>The wrong term for the X Window System. See <TT>X Window System</TT>.
<DT><B><TT>yacc</TT>
</B>
<DD>Yet another compiler compiler.
</DL>

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