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<HTML><!--Distributed by F --><HEAD><TITLE>Glossary</TITLE><METANAME="DC.title"CONTENT="UNIX Power Tools"><METANAME="DC.creator"CONTENT="Jerry Peek, Tim O'Reilly & Mike Loukides"><METANAME="DC.publisher"CONTENT="O'Reilly & Associates, Inc."><METANAME="DC.date"CONTENT="1998-08-04T21:59:10Z"><METANAME="DC.type"CONTENT="Text.Monograph"><METANAME="DC.format"CONTENT="text/html"SCHEME="MIME"><METANAME="DC.source"CONTENT="1-56592-260-3"SCHEME="ISBN"><METANAME="DC.language"CONTENT="en-US"><METANAME="generator"CONTENT="Jade 1.1/O'Reilly DocBook 3.0 to HTML 4.0"><LINKREV="made"HREF="mailto:online-books@oreilly.com"TITLE="Online Books Comments"><LINKREL="up"HREF="part09.htm"TITLE="IX. Miscellaneous "><LINKREL="prev"HREF="ch52_09.htm"TITLE="52.9 Software Support from RTR "></HEAD><BODYBGCOLOR="#FFFFFF"TEXT="#000000"><DIVCLASS="htmlnav"><H1><IMGSRC="gifs/smbanner.gif"ALT="UNIX Power Tools"USEMAP="#srchmap"BORDER="0"></H1><MAPNAME="srchmap"><AREASHAPE="RECT"COORDS="0,0,466,58"HREF="index.htm"ALT="UNIX Power Tools"><AREASHAPE="RECT"COORDS="467,0,514,18"HREF="jobjects/fsearch.htm"ALT="Search this book"></MAP><TABLEWIDTH="515"BORDER="0"CELLSPACING="0"CELLPADDING="0"><TR><TDALIGN="LEFT"VALIGN="TOP"WIDTH="172"><ACLASS="SECT1"HREF="ch52_09.htm"TITLE="52.9 Software Support from RTR "><IMGSRC="gifs/txtpreva.gif"SRC="gifs/txtpreva.gif"ALT="Previous: 52.9 Software Support from RTR "BORDER="0"></A></TD><TDALIGN="CENTER"VALIGN="TOP"WIDTH="171"><B><FONTFACE="ARIEL,HELVETICA,HELV,SANSERIF"SIZE="-1">Glossary</FONT></B></TD><TDALIGN="RIGHT"VALIGN="TOP"WIDTH="172"> </TD></TR></TABLE> <HRALIGN="LEFT"WIDTH="515"TITLE="footer"></DIV><DLCLASS="GLOSSARY"><H1CLASS="glossary"><ACLASS="title"NAME="UPT-ART-1010">Glossary</A></H1><DTCLASS="glossterm"><ACLASS="glossterm"NAME="GLOSS-AIX">AIX</A></DT><DDCLASS="glossdef"><PCLASS="para">A version of UNIX from the IBM Corporation.</P></DD><DTCLASS="glossterm"><ACLASS="glossterm"NAME="GLOSS-ARGUMENT">argument</A></DT><DDCLASS="glossdef"><PCLASS="para">Zero or more characters passed to a program as a single unit.The shell breaks a command line into arguments by cutting it atunquoted white space. <EMCLASS="emphasis">See also</EM> article<ACLASS="xref"HREF="ch08_05.htm"TITLE="Command-Line Evaluation ">8.5</A>,<ACLASS="xref"HREF="glossary.htm#GLOSS-WORD"TITLE="">word</A>.</P></DD><DTCLASS="glossterm"><ACLASS="glossterm"NAME="GLOSS-ARRAY">array</A></DT><DDCLASS="glossdef"><PCLASS="para">An ordered collection of data items.An array has a single overall name; each item in it is called an <EMCLASS="emphasis">element</EM>or <EMCLASS="emphasis">member</EM>.For instance, the C shell stores its command search path in an<SPANCLASS="link">array (<ACLASS="linkend"HREF="ch47_05.htm"TITLE="Using C Shell Arrays ">47.5</A>)</SPAN>named<SPANCLASS="link"><EMCLASS="emphasis">path</EM> (<ACLASS="linkend"HREF="ch06_05.htm"TITLE="PATH and path ">6.5</A>)</SPAN>.The first array member is named <CODECLASS="literal">$path[1]</CODE>, the second is<CODECLASS="literal">$path[2]</CODE>, and so on.</P></DD><DTCLASS="glossterm"><ACLASS="glossterm"NAME="GLOSS-ASCII-FILE">ASCII file</A></DT><DDCLASS="glossdef"><PCLASS="para">Formally, a file containing only<SPANCLASS="link">ASCII (<ACLASS="linkend"HREF="ch51_03.htm"TITLE="ASCII Characters: Listing and Getting Values ">51.3</A>)</SPAN>characters.More commonly (in the USA, at least) a file containing text that'sprintable, viewable, and has no "binary" (non-ASCII) characters.ASCII characters use only seven of the bits in a (8-bit) byte.</P></DD><DTCLASS="glossterm"><ACLASS="glossterm"NAME="GLOSS-BACKQUOTE">backquote</A></DT><DDCLASS="glossdef"><PCLASS="para">The character <CODECLASS="literal">`</CODE>.Not the same as a single quote (<CODECLASS="literal">'</CODE>).Does<SPANCLASS="link">command substitution (<ACLASS="linkend"HREF="ch09_16.htm"TITLE="Command Substitution ">9.16</A>)</SPAN>.</P></DD><DTCLASS="glossterm"><ACLASS="glossterm"NAME="GLOSS-BACKSLASH">backslash</A></DT><DDCLASS="glossdef"><PCLASS="para">The character <CODECLASS="literal">\</CODE>.In UNIX, it changes the interpretation of the next character in some way.<EMCLASS="emphasis">See also</EM> article<ACLASS="xref"HREF="ch08_20.htm"TITLE="How Many Backslashes?">8.20</A>,<ACLASS="xref"HREF="glossary.htm#GLOSS-SLASH"TITLE="">slash</A>.</P></DD><DTCLASS="glossterm"><ACLASS="glossterm"NAME="GLOSS-BATCH-QUEUE">batch queue</A></DT><DDCLASS="glossdef"><PCLASS="para">A mechanism for sequencing large jobs. A batch queue receives jobrequests from users. It then executes the jobs one at a time. Batchqueues go back to the earliest days of data processing. They are anextremely effective, if uncomfortable, way to manage system load.<EMCLASS="emphasis">See also</EM> article<ACLASS="xref"HREF="ch40_06.htm"TITLE="System V.4 Batch Queues ">40.6</A>.</P></DD><DTCLASS="glossterm"><ACLASS="glossterm"NAME="GLOSS-BIN-DIRECTORY">bin directory</A></DT><DDCLASS="glossdef"><PCLASS="para">A directory for storing executable programs.<EMCLASS="emphasis">See also</EM> article<ACLASS="xref"HREF="ch04_02.htm"TITLE="A bin Directory for Your Programs and Scripts ">4.2</A>.</P></DD><DTCLASS="glossterm"><ACLASS="glossterm"NAME="GLOSS-BINARIES-BINARY-FILE">binaries, binary file</A></DT><DDCLASS="glossdef"><PCLASS="para">A file with non-text characters.Often, a directly executable file that can be run as a program.Binary characters use all the bits in a (8-bit) byte.<EMCLASS="emphasis">See also</EM><ACLASS="xref"HREF="glossary.htm#GLOSS-ASCII-FILE"TITLE="">ASCII file</A>.</P></DD><DTCLASS="glossterm"><ACLASS="glossterm"NAME="GLOSS-BLOCK-SIZE">block size</A></DT><DDCLASS="glossdef"><PCLASS="para">The largest amount of data that a UNIX filesystem will alwaysallocate contiguously. For example, if a filesystem's block size is 8KB, files of size up to 8 KB are always physically contiguous (i.e.,in one place), rather than spread across the disk. Files that arelarger than the filesystem's block size may be fragmented: 8 KB pieces ofthe file are located in different places on the disk. Fragmentationlimits filesystem performance. Note that the filesystem block size isdifferent from a disk's physical block size, which is almost always 512 bytes.</P></DD><DTCLASS="glossterm"><ACLASS="glossterm"NAME="GLOSS-BRAIN-DAMAGED">brain-damaged</A></DT><DDCLASS="glossdef"><PCLASS="para">A program with poor design or other errors can be called <EMCLASS="emphasis">brain-damaged</EM>.</P></DD><DTCLASS="glossterm"><ACLASS="glossterm"NAME="GLOSS-BSD-UNIX">BSD UNIX</A></DT><DDCLASS="glossdef"><PCLASS="para">The versions of UNIX developed at the University of California,Berkeley. BSD UNIX has been dominant in academia and hashistorically had some more advanced features than System V: BSDintroduced virtual memory, networking, and the "fast filesystem" tothe UNIX community. It is also the system on which SunOS was based.System V Release 4 and some vendors' earlier System V versionsalso have Berkeley features.</P></DD><DTCLASS="glossterm"><ACLASS="glossterm"NAME="GLOSS-BUFFER">buffer</A></DT><DDCLASS="glossdef"><PCLASS="para">A temporary storage place such as a file or an area of the computer'smemory.Most text editors store the file you're editing in a buffer; when you'redone editing, the edited buffer is copied over (i.e., replaces) the original file.</P></DD><DTCLASS="glossterm"><ACLASS="glossterm"NAME="GLOSS-COMMAND-LINE">command line</A></DT><DDCLASS="glossdef"><PCLASS="para">The text you type at a shell prompt.A UNIX shell reads the command line, parses it to find the command name(which is the first word on the command line), and executes the command.A command line may have more than one command joined by operators like<SPANCLASS="link">semicolons (<CODECLASS="literal">;</CODE>) (<ACLASS="linkend"HREF="ch08_05.htm"TITLE="Command-Line Evaluation ">8.5</A>)</SPAN>,<SPANCLASS="link">pipes (<CODECLASS="literal">|</CODE>) (<ACLASS="linkend"HREF="ch01_04.htm"TITLE="Using Pipes to Create a New Tool ">1.4</A>)</SPAN>,or<SPANCLASS="link">double ampersands (<CODECLASS="literal">&&</CODE>) (<ACLASS="linkend"HREF="ch44_09.htm"TITLE="Testing Your Success ">44.9</A>)</SPAN>.</P></DD><DTCLASS="glossterm"><ACLASS="glossterm"NAME="GLOSS-CONTROL-CHARACTER">control character</A></DT><DDCLASS="glossdef"><PCLASS="para">A character you make by holding down the keyboard CTRL (Control) keywhile pressing a letter or another character key.</P></DD><DTCLASS="glossterm"><ACLASS="glossterm"NAME="GLOSS-CORE-FILE-CORE-DUMP">core file, core dump</A></DT><DDCLASS="glossdef"><PCLASS="para">When a program terminates abnormally, it may make a file named <EMCLASS="emphasis">core</EM>.The <EMCLASS="emphasis">core</EM> file can be used for debugging.<EMCLASS="emphasis">See also</EM> article<ACLASS="xref"HREF="ch24_05.htm"TITLE="Limiting File Sizes ">24.5</A>.</P></DD><DTCLASS="glossterm"><ACLASS="glossterm"NAME="GLOSS-.CSHRC-FILE">.cshrc file</A></DT><DDCLASS="glossdef"><PCLASS="para"><EMCLASS="emphasis">See</EM><ACLASS="xref"HREF="glossary.htm#GLOSS-DOT-FILES"TITLE="">dot (.) files (.cshrc, .login, .profile</A>.</P></DD><DTCLASS="glossterm"><ACLASS="glossterm"NAME="GLOSS-CTRL-X">CTRL-x</A></DT><DDCLASS="glossdef"><PCLASS="para">The character called "control <EMCLASS="emphasis">x</EM>," where <EMCLASS="emphasis">x</EM> is a key on the keyboard.<EMCLASS="emphasis">See also</EM><ACLASS="xref"HREF="glossary.htm#GLOSS-CONTROL-CHARACTER"TITLE="">control character</A>.</P></DD><DTCLASS="glossterm"><ACLASS="glossterm"NAME="GLOSS-DAEMON">daemon</A></DT><DDCLASS="glossdef"><PCLASS="para">A program that is invisible to users but provides important systemservices. Daemons manage everything from paging to networking tonotification of incoming mail. BSD UNIX has many different daemons:without counting, I would guess that there are roughly two dozen.Daemons normally spend most of their time "sleeping" or waiting for something to do, so that they don'taccount for a lot of CPU load.<EMCLASS="emphasis">See also</EM> article<ACLASS="xref"HREF="ch01_14.htm"TITLE="The Kernel and Daemons ">1.14</A>.</P></DD><DTCLASS="glossterm"><ACLASS="glossterm"NAME="GLOSS-DATA-SWITCH">data switch</A></DT><DDCLASS="glossdef"><PCLASS="para">This hardware is something like a telephone switchboard.A data switch connects many terminals to two or more computers.The user, on a terminal or through a modem, tells the data switch whichcomputer she wants a connection to.Also called a <EMCLASS="emphasis">terminal multiplexor</EM>.Computers without data switches usually have one terminal connected toeach<SPANCLASS="link"><EMCLASS="emphasis">tty</EM> (<ACLASS="linkend"HREF="ch03_08.htm"TITLE="What tty Am I On? ">3.8</A>)</SPAN>port; characteristics like the<SPANCLASS="link">terminal type (<ACLASS="linkend"HREF="ch05_10.htm"TITLE="Finding What Terminal Names You Can Use ">5.10</A>)</SPAN>can be set in system files.Conversely,computers with data switches can't know in advance what sort of terminalis connected to each <EMCLASS="emphasis">tty</EM> port.</P></DD><DTCLASS="glossterm"><A⌨️ 快捷键说明
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