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5.5 KiB
HTML
89 lines
5.5 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3O//DTD W3 HTML 2.0//EN">
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<!Converted with LaTeX2HTML 0.6.5 (Tue Nov 15 1994) by Nikos Drakos (nikos@cbl.leeds.ac.uk), CBLU, University of Leeds >
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<HEAD>
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<TITLE>23.1. File Names</TITLE>
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</HEAD>
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<BODY>
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<meta name="description" value=" File Names">
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<meta name="keywords" value="clm">
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<meta name="resource-type" value="document">
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<meta name="distribution" value="global">
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<P>
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<b>Common Lisp the Language, 2nd Edition</b>
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<BR> <HR><A NAME=tex2html4084 HREF="node204.html"><IMG ALIGN=BOTTOM ALT="next" SRC="icons/next_motif.gif"></A> <A NAME=tex2html4082 HREF="node202.html"><IMG ALIGN=BOTTOM ALT="up" SRC="icons/up_motif.gif"></A> <A NAME=tex2html4076 HREF="node202.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="icons/previous_motif.gif"></A> <A NAME=tex2html4086 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="icons/contents_motif.gif"></A> <A NAME=tex2html4087 HREF="index.html"><IMG ALIGN=BOTTOM ALT="index" SRC="icons/index_motif.gif"></A> <BR>
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<B> Next:</B> <A NAME=tex2html4085 HREF="node204.html"> Pathnames</A>
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<B>Up:</B> <A NAME=tex2html4083 HREF="node202.html"> File System Interface</A>
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<B> Previous:</B> <A NAME=tex2html4077 HREF="node202.html"> File System Interface</A>
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<HR> <P>
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<H1><A NAME=SECTION002710000000000000000>23.1. File Names</A></H1>
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<P>
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Common Lisp programs need to use names to designate files.
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The main difficulty in dealing with names of files is that different
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file systems have different naming formats for files.
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For example, here is a table of several file systems (actually,
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operating systems that provide file systems) and what equivalent
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file names might look like for each one:
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<pre>
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System File Name
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==================================================
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TOPS-20 <LISPIO>FORMAT.FASL.13
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TOPS-10 FORMAT.FAS[1,4]
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ITS LISPIO;FORMAT FASL
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MULTICS >udd>LispIO>format.fasl
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TENEX <LISPIO>FORMAT.FASL;13
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VAX/VMS [LISPIO]FORMAT.FAS;13
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UNIX /usr/lispio/format.fasl
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==================================================
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</pre>
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It would be impossible for each program that deals with file names to
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know about each different file name format that exists; a new Common Lisp
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implementation might use a format different from any of its predecessors.
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Therefore, Common Lisp provides <i>two</i> ways to represent file names:
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<i>namestrings</i>, which are strings in the implementation-dependent form
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customary for the file system, and <i>pathnames</i>, which are special abstract
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data objects that represent file names in an implementation-independent
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way. Functions are provided to convert between these two representations,
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and all manipulations of files can be expressed in machine-independent
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terms by using pathnames.
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<P>
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In order to allow Common Lisp programs to operate in a network environment
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that may have more than one kind of file system, the pathname facility
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allows a file name to specify which file system is to be used.
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In this context, each file system is called a <i>host</i>, in keeping
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with the usual networking terminology.
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<P>
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<img align=bottom alt="change_begin" src="gif/change_begin.gif"><br>
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Different hosts may use different notations for file names.
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Common Lisp allows customary notation to be used for each host, but
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also supports
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a system of logical pathnames that provides a standard framework for naming
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files in a portable manner (see section <A HREF="node208.html#LOGICALPATHNAMESSECTION">23.1.5</A>).
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<br><img align=bottom alt="change_end" src="gif/change_end.gif">
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<P>
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<HR>
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<UL>
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<LI> <A NAME=tex2html4088 HREF="node204.html#SECTION002711000000000000000"> Pathnames</A>
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<LI> <A NAME=tex2html4089 HREF="node205.html#SECTION002712000000000000000"> Case Conventions</A>
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<LI> <A NAME=tex2html4090 HREF="node206.html#SECTION002713000000000000000"> Structured Directories</A>
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<LI> <A NAME=tex2html4091 HREF="node207.html#SECTION002714000000000000000"> Extended Wildcards</A>
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<LI> <A NAME=tex2html4092 HREF="node208.html#SECTION002715000000000000000"> Logical Pathnames</A>
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<UL>
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<LI> <A NAME=tex2html4093 HREF="node209.html#SECTION002715100000000000000"> Syntax of Logical Pathname Namestrings</A>
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<LI> <A NAME=tex2html4094 HREF="node210.html#SECTION002715200000000000000"> Parsing of Logical Pathname Namestrings</A>
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<LI> <A NAME=tex2html4095 HREF="node211.html#SECTION002715300000000000000"> Using Logical Pathnames</A>
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<LI> <A NAME=tex2html4096 HREF="node212.html#SECTION002715400000000000000"> Examples of the Use of Logical Pathnames</A>
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<LI> <A NAME=tex2html4097 HREF="node213.html#SECTION002715500000000000000"> Discussion of Logical Pathnames</A>
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</UL>
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<LI> <A NAME=tex2html4098 HREF="node214.html#SECTION002716000000000000000"> Pathname Functions</A>
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</UL>
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<BR> <HR><A NAME=tex2html4084 HREF="node204.html"><IMG ALIGN=BOTTOM ALT="next" SRC="icons/next_motif.gif"></A> <A NAME=tex2html4082 HREF="node202.html"><IMG ALIGN=BOTTOM ALT="up" SRC="icons/up_motif.gif"></A> <A NAME=tex2html4076 HREF="node202.html"><IMG ALIGN=BOTTOM ALT="previous" SRC="icons/previous_motif.gif"></A> <A NAME=tex2html4086 HREF="node1.html"><IMG ALIGN=BOTTOM ALT="contents" SRC="icons/contents_motif.gif"></A> <A NAME=tex2html4087 HREF="index.html"><IMG ALIGN=BOTTOM ALT="index" SRC="icons/index_motif.gif"></A> <BR>
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<B> Next:</B> <A NAME=tex2html4085 HREF="node204.html"> Pathnames</A>
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<B>Up:</B> <A NAME=tex2html4083 HREF="node202.html"> File System Interface</A>
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<B> Previous:</B> <A NAME=tex2html4077 HREF="node202.html"> File System Interface</A>
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<HR> <P>
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<HR>
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<P><ADDRESS>
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AI.Repository@cs.cmu.edu
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</ADDRESS>
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</BODY>
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