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<pre>
<code style="font-family: Courier New, Courier, monospace; font-size: 12">
~/tcltk$ <b>tclsh</b>
% <b>file exists hello3.tcl</b>
1
% <b>file executable testit</b>
0
% <b>file pathtype ./hello3.tcl</b>
relative
% <b>set dir1 home</b>
home
% <b>set dir2 brian</b>
brian
% <b>set dir3 tcltk</b>
tcltk
% <b>file join /$dir1 dir2 dir3</b>
/home/dir2/dir3 
% <b>file delete testit~</b>
%
			</code>
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<td width="90%"><font size="4" face="Verdana, Arial, Helvetica"><b>Paths and files</b></font></td><td width="200" align="right"><font size="1" face="Verdana, Arial, Helvetica"><nobr>   第 13 页（共15 页）</nobr></font></td>
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<p>File and path operations are a challenging problem in 
				a cross-platform environment. Tcl uses UNIX pathnames 
				(separated using the '/' character by default), as well as 
				the native pathname construction for the host OS. Even when 
				in-program data is constructed properly, it can be difficult 
				to ensure that user input matches the system requirements. 
				The <i>file join</i> command is used to convert UNIX formats 
				to native pathnames. Other path string commands include 
				<i>file split</i>, <i>dirname</i>, <i>file extension</i>, 
				<i>nativename</i>, <i>pathtype</i>, and <i>tail</i>.</p>
<p>In its role as a "Tool Control Language", Tcl has a wide 
				variety of internal file test and operation features. Each 
				command leads off with <i>file</i>, as in <i>file exists 
				name</i>. Other test commands (which 
				all return boolean values) include <i>executable</i>, 
				<i>isdirectory</i>, <i>isfile</i>, <i>owned</i>, 
				<i>readable</i>, and <i>writable</i>.</p>
<p>File information and operations are accomplished (again, all 
				with the leading <i>file</i>) <i>atime</i>, <i>attributes</i>, 
				<i>copy</i>, <i>delete</i>, <i>lstat</i>, <i>mkdir</i>, 
				<i>mtime</i>, <i>readlink</i>, <i>rename</i>, <i>rootname</i>, 
				<i>size</i>, <i>stat</i>, and <i>type</i>. Note that a number of 
				the file information commands may return undefined data when 
				running in the Windows or Mac environments, since, for example, 
				inode and symbolic (<i>and</i> hard) link data isn't represented in 
				those file systems.</p>
<p>The advantage of using <i>file ...</i> commands rather than using 
				native commands via <i>exec</i> is that the former presents a 
				portable interface.</p>
<p>This whole document could easily be devoted to just this one 
				section of the Tcl language. However, content 
				yourself with the <i>tclsh</i> examples to the left, which reveal
				the flavor of  these commands, and then follow up with 
				readings from the Resources listed at the end of the tutorial.</p>
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