Zlib.html 30 KB
Newer Older
1 2 3
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
4 5
<head>
  <title>IO::Zlib - perldoc.perl.org</title>
6 7
  <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
  <meta http-equiv="Content-Language" content="en-gb">
8 9 10
  <link rel="search" type="application/opensearchdescription+xml" title="Search perldoc.perl.org" href="/static/search.xml"/>
  <link href="../static/css-20100830.css" rel="stylesheet" rev="stylesheet" type="text/css" media="screen">
  <link href="../static/exploreperl.css" rel="stylesheet" rev="stylesheet" type="text/css">
11 12
</head>

13 14 15 16 17 18 19
<body onLoad="perldoc.startup();" onPageShow="if (event.persisted) perldoc.startup();">
    <div id="page">
      
      <div id="header">
	<div id="homepage_link">
	  <a href="../index.html"></a>
	</div>
20 21 22 23 24 25 26 27 28
	<div id="strapline">
	  Perl Programming Documentation
	</div>
	<div id="download_link" class="download">
	  <a href="http://www.perl.org/get.html">Download Perl</a>
	</div>
	<div id="explore_link" class="download">
	  <a id="explore_anchor" href="#">Explore</a>
	</div>
29
      </div>
30 31 32 33
      
      <div id="body">
        <div id="left_column">
          <div class="side_group">
34 35
            
	    <div class="side_panel doc_panel">
36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53
              <p>Manual</p>
              <ul>
                <li><a href="../index-overview.html">Overview</a>
                <li><a href="../index-tutorials.html">Tutorials</a>
                <li><a href="../index-faq.html">FAQs</a>
                <li><a href="../index-history.html">History / Changes</a>
                <li><a href="../index-licence.html">License</a>
              </ul>
            </div>
            <div class="side_panel doc_panel">
              <p>Reference</p>
              <ul>
                <li><a href="../index-language.html">Language</a>
                <li><a href="../index-functions.html">Functions</a>
                <li><a href="../perlop.html">Operators</a>
                <li><a href="../perlvar.html">Special Variables</a>
                <li><a href="../index-pragmas.html">Pragmas</a>
                <li><a href="../index-utilities.html">Utilities</a>
54
                <li><a href="../index-internals.html">Internals</a>
55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276
                <li><a href="../index-platforms.html">Platform Specific</a>
              </ul>
            </div>
            <div class="side_panel doc_panel">
              <p>Modules</p>
              <ul>
		<li>
		
                
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		
                  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		
                  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		    
		  
		
                  
		
                  
		
                  
		    
		  
		
                  
		
                  
		
		
                    <a href="../index-modules-A.html">A</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="../index-modules-B.html">B</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="../index-modules-C.html">C</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="../index-modules-D.html">D</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="../index-modules-E.html">E</a>
                    
                      
                        <li>
                      
                    
                
                    <a href="../index-modules-F.html">F</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="../index-modules-G.html">G</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="../index-modules-H.html">H</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="../index-modules-I.html">I</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="../index-modules-L.html">L</a>
                    
                      
                        <li>
                      
                    
                
                    <a href="../index-modules-M.html">M</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="../index-modules-N.html">N</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="../index-modules-O.html">O</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="../index-modules-P.html">P</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="../index-modules-S.html">S</a>
                    
                      
                        <li>
                      
                    
                
                    <a href="../index-modules-T.html">T</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="../index-modules-U.html">U</a>
                    
                      
                        &bull;
                      
                    
                
                    <a href="../index-modules-X.html">X</a>
                    
                
              </ul>
            </div>
277 278 279 280 281 282 283 284
            
	      <div class="side_panel doc_panel">
		<p>Tools</p>
		<ul>
		  <li><a href="../preferences.html">Preferences</a>
		</ul>
	      </div>
            
285 286 287 288 289 290 291 292 293
          </div>
        </div>
        <div id="centre_column">
          <div id="content_header">
            <div id="title_bar">
              <div id="page_name">
                <h1>IO::Zlib</h1>
              </div>
              <div id="perl_version">
294
                Perl 5 version 26.0 documentation
295
              </div>
296
              <div class="page_links" id="page_links_top">
297 298
                <a href="#" onClick="toolbar.goToTop();return false;">Go to top</a>
		
299 300
              </div>
	      <div class="page_links" id="page_links_bottom">
301
		
302
                  <a href="#" id="page_index_toggle">Show page index</a> &bull;
303
		
304 305 306 307 308 309 310
                <a href="#" id="recent_pages_toggle">Show recent pages</a>		
	      </div>
	      <div id="search_form">
		<form action="../search.html" method="GET" id="search">
		  <input type="text" name="q" id="search_box" alt="Search">
		</form>
	      </div>
311 312 313 314 315 316 317 318 319 320 321
            </div>
            <div id="breadcrumbs">
                
    <a href="../index.html">Home</a> &gt;
    
      
        <a href="../index-modules-I.html">Core modules (I)</a> &gt;
      
    
    IO::Zlib
  
322

323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362
            </div>
          </div>
          <div id="content_body">
	    <!--[if lt IE 7]>
 <div class="noscript">
   <p>
     <strong>It looks like you're using Internet Explorer 6. This is a very old
     browser which does not offer full support for modern websites.</strong>
   </p>
   <p>
     Unfortunately this means that this website will not work on
     your computer.
   </p>
   <p>
     Don't miss out though! To view the site (and get a better experience from
     many other websites), simply upgrade to
     <a href="http://www.microsoft.com/windows/Internet-explorer/default.aspx">Internet
Explorer 8</a>
     or download an alternative browser such as
     <a href="http://www.mozilla.com/en-US/firefox/firefox.html">Firefox</a>,
     <a href="http://www.apple.com/safari/download/">Safari</a>, or
     <a href="http://www.google.co.uk/chrome">Google Chrome</a>.
   </p>
   <p>
     All of these browsers are free. If you're using a PC at work, you may
     need to contact your IT administrator.
   </p>
 </div>
<![endif]-->
	    <noscript>
	      <div class="noscript">
	      <p>
                <strong>Please note: Many features of this site require JavaScript. You appear to have JavaScript disabled,
	        or are running a non-JavaScript capable web browser.</strong>
	      </p>
	      <p>
		To get the best experience, please enable JavaScript or download a modern web browser such as <a href="http://www.microsoft.com/windows/Internet-explorer/default.aspx">Internet Explorer 8</a>, <a href="http://www.mozilla.com/en-US/firefox/firefox.html">Firefox</a>, <a href="http://www.apple.com/safari/download/">Safari</a>, or <a href="http://www.google.co.uk/chrome">Google Chrome</a>.
              </p>
	      </div>
	    </noscript>
363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378

	    <div id="recent_pages" class="hud_container">
	      <div id="recent_pages_header" class="hud_header">
		<div id="recent_pages_close" class="hud_close"><a href="#" onClick="recentPages.hide();return false;"></a></div>
		<div id="recent_pages_title" class="hud_title"><span class="hud_span_top">Recently read</span></div>
		<div id="recent_pages_topright" class="hud_topright"></div>
	      </div>
	      <div id="recent_pages_content" class="hud_content">
	      </div>
	      <div id="recent_pages_footer" class="hud_footer">
		<div id="recent_pages_bottomleft" class="hud_bottomleft"></div>
		<div id="recent_pages_bottom" class="hud_bottom"><span class="hud_span_bottom"></span></div>
		<div id="recent_pages_resize" class="hud_resize"></div>
	      </div>
	    </div>
  
379 380 381 382 383 384
	    <div id="from_search"></div>
            <h1>IO::Zlib</h1>


  <!--    -->
<ul><li><a href="#NAME">NAME</a><li><a href="#SYNOPSIS">SYNOPSIS</a><li><a href="#DESCRIPTION">DESCRIPTION</a><li><a href="#CONSTRUCTOR">CONSTRUCTOR</a><li><a href="#OBJECT-METHODS">OBJECT METHODS</a><li><a href="#USING-THE-EXTERNAL-GZIP">USING THE EXTERNAL GZIP</a><li><a href="#CLASS-METHODS">CLASS METHODS</a><li><a href="#DIAGNOSTICS">DIAGNOSTICS</a><li><a href="#SEE-ALSO">SEE ALSO</a><li><a href="#HISTORY">HISTORY</a><li><a href="#COPYRIGHT">COPYRIGHT</a></ul><a name="NAME"></a><h1>NAME</h1>
385 386 387
<p>IO::Zlib - IO:: style interface to <a href="../Compress/Zlib.html">Compress::Zlib</a></p>
<a name="SYNOPSIS"></a><h1>SYNOPSIS</h1>
<p>With any version of Perl 5 you can use the basic OO interface:</p>
388
<pre class="verbatim"><ol><li>    <a class="l_k" href="../functions/use.html">use</a> <span class="w">IO::Zlib</span><span class="sc">;</span></li><li></li><li>    <span class="i">$fh</span> = <span class="w">new</span> <span class="w">IO::Zlib</span><span class="sc">;</span></li><li>    if <span class="s">(</span><span class="i">$fh</span><span class="i">-&gt;open</span><span class="s">(</span><span class="q">&quot;file.gz&quot;</span><span class="cm">,</span> <span class="q">&quot;rb&quot;</span><span class="s">)</span><span class="s">)</span> <span class="s">{</span></li><li>        <a class="l_k" href="../functions/print.html">print</a> <span class="q">&lt;$fh&gt;</span><span class="sc">;</span></li><li>        <span class="i">$fh</span><span class="i">-&gt;close</span><span class="sc">;</span></li><li>    <span class="s">}</span></li><li></li><li>    <span class="i">$fh</span> = <span class="w">IO::Zlib</span><span class="w">-&gt;new</span><span class="s">(</span><span class="q">&quot;file.gz&quot;</span><span class="cm">,</span> <span class="q">&quot;wb9&quot;</span><span class="s">)</span><span class="sc">;</span></li><li>    if <span class="s">(</span><a class="l_k" href="../functions/defined.html">defined</a> <span class="i">$fh</span><span class="s">)</span> <span class="s">{</span></li><li>        <a class="l_k" href="../functions/print.html">print</a> <span class="i">$fh</span> <span class="q">&quot;bar\n&quot;</span><span class="sc">;</span></li><li>        <span class="i">$fh</span><span class="i">-&gt;close</span><span class="sc">;</span></li><li>    <span class="s">}</span></li><li></li><li>    <span class="i">$fh</span> = <span class="w">IO::Zlib</span><span class="w">-&gt;new</span><span class="s">(</span><span class="q">&quot;file.gz&quot;</span><span class="cm">,</span> <span class="q">&quot;rb&quot;</span><span class="s">)</span><span class="sc">;</span></li><li>    if <span class="s">(</span><a class="l_k" href="../functions/defined.html">defined</a> <span class="i">$fh</span><span class="s">)</span> <span class="s">{</span></li><li>        <a class="l_k" href="../functions/print.html">print</a> <span class="q">&lt;$fh&gt;</span><span class="sc">;</span></li><li>        <a class="l_k" href="../functions/undef.html">undef</a> <span class="i">$fh</span><span class="sc">;</span>       <span class="c"># automatically closes the file</span></li><li>    <span class="s">}</span></li></ol></pre><p>With Perl 5.004 you can also use the TIEHANDLE interface to access
389
compressed files just like ordinary files:</p>
390
<pre class="verbatim"><ol><li>    <a class="l_k" href="../functions/use.html">use</a> <span class="w">IO::Zlib</span><span class="sc">;</span></li><li></li><li>    <a class="l_k" href="../functions/tie.html">tie</a> <span class="i">*FILE</span><span class="cm">,</span> <span class="q">&#39;IO::Zlib&#39;</span><span class="cm">,</span> <span class="q">&quot;file.gz&quot;</span><span class="cm">,</span> <span class="q">&quot;wb&quot;</span><span class="sc">;</span></li><li>    <a class="l_k" href="../functions/print.html">print</a> <span class="i">FILE</span> <span class="q">&quot;line 1\nline2\n&quot;</span><span class="sc">;</span></li><li></li><li>    <a class="l_k" href="../functions/tie.html">tie</a> <span class="i">*FILE</span><span class="cm">,</span> <span class="q">&#39;IO::Zlib&#39;</span><span class="cm">,</span> <span class="q">&quot;file.gz&quot;</span><span class="cm">,</span> <span class="q">&quot;rb&quot;</span><span class="sc">;</span></li><li>    while <span class="s">(</span><span class="q">&lt;FILE&gt;</span><span class="s">)</span> <span class="s">{</span> <a class="l_k" href="../functions/print.html">print</a> <span class="q">&quot;LINE: &quot;</span><span class="cm">,</span> <span class="i">$_</span> <span class="s">}</span><span class="sc">;</span></li></ol></pre><a name="DESCRIPTION"></a><h1>DESCRIPTION</h1>
391 392 393 394 395 396 397 398 399
<p><code class="inline"><span class="w">IO::Zlib</span></code>
 provides an IO:: style interface to <a href="../Compress/Zlib.html">Compress::Zlib</a> and
hence to gzip/zlib compressed files. It provides many of the same methods
as the <a href="../IO/Handle.html">IO::Handle</a> interface.</p>
<p>Starting from IO::Zlib version 1.02, IO::Zlib can also use an
external <i>gzip</i> command.  The default behaviour is to try to use
an external <i>gzip</i> if no <code class="inline"><span class="w">Compress::Zlib</span></code>
 can be loaded, unless
explicitly disabled by</p>
400 401
<pre class="verbatim"><ol><li>    <a class="l_k" href="../functions/use.html">use</a> <span class="w">IO::Zlib</span> <span class="q">qw(:gzip_external 0)</span><span class="sc">;</span></li></ol></pre><p>If explicitly enabled by</p>
<pre class="verbatim"><ol><li>    <a class="l_k" href="../functions/use.html">use</a> <span class="w">IO::Zlib</span> <span class="q">qw(:gzip_external 1)</span><span class="sc">;</span></li></ol></pre><p>then the external <i>gzip</i> is used <b>instead</b> of <code class="inline"><span class="w">Compress::Zlib</span></code>
402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435
.</p>
<a name="CONSTRUCTOR"></a><h1>CONSTRUCTOR</h1>
<ul>
<li><a name="new-(-%5bARGS%5d-)"></a><b>new ( [ARGS] )</b>
<p>Creates an <code class="inline"><span class="w">IO::Zlib</span></code>
 object. If it receives any parameters, they are
passed to the method <code class="inline"><a class="l_k" href="../functions/open.html">open</a></code>; if the open fails, the object is destroyed.
Otherwise, it is returned to the caller.</p>
</li>
</ul>
<a name="OBJECT-METHODS"></a><h1>OBJECT METHODS</h1>
<ul>
<li><a name="open-(-FILENAME%2c-MODE-)"></a><b>open ( FILENAME, MODE )</b>
<p><code class="inline"><a class="l_k" href="../functions/open.html">open</a></code> takes two arguments. The first is the name of the file to open
and the second is the open mode. The mode can be anything acceptable to
<a href="../Compress/Zlib.html">Compress::Zlib</a> and by extension anything acceptable to <i>zlib</i> (that
basically means POSIX fopen() style mode strings plus an optional number
to indicate the compression level).</p>
</li>
<li><a name="opened"></a><b>opened</b>
<p>Returns true if the object currently refers to a opened file.</p>
</li>
<li><a name="close"></a><b>close</b>
<p>Close the file associated with the object and disassociate
the file from the handle.
Done automatically on destroy.</p>
</li>
<li><a name="getc"></a><b>getc</b>
<p>Return the next character from the file, or undef if none remain.</p>
</li>
<li><a name="getline"></a><b>getline</b>
<p>Return the next line from the file, or undef on end of string.
Can safely be called in an array context.
Currently ignores $/ ($INPUT_RECORD_SEPARATOR or $RS when <a href="../English.html">English</a>
436
is in use) and treats lines as delimited by "\n".</p>
437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471
</li>
<li><a name="getlines"></a><b>getlines</b>
<p>Get all remaining lines from the file.
It will croak() if accidentally called in a scalar context.</p>
</li>
<li><a name="print-(-ARGS...-)"></a><b>print ( ARGS... )</b>
<p>Print ARGS to the  file.</p>
</li>
<li><a name="read-(-BUF%2c-NBYTES%2c-%5bOFFSET%5d-)"></a><b>read ( BUF, NBYTES, [OFFSET] )</b>
<p>Read some bytes from the file.
Returns the number of bytes actually read, 0 on end-of-file, undef on error.</p>
</li>
<li><a name="eof"></a><b>eof</b>
<p>Returns true if the handle is currently positioned at end of file?</p>
</li>
<li><a name="seek-(-OFFSET%2c-WHENCE-)"></a><b>seek ( OFFSET, WHENCE )</b>
<p>Seek to a given position in the stream.
Not yet supported.</p>
</li>
<li><a name="tell"></a><b>tell</b>
<p>Return the current position in the stream, as a numeric offset.
Not yet supported.</p>
</li>
<li><a name="setpos-(-POS-)"></a><b>setpos ( POS )</b>
<p>Set the current position, using the opaque value returned by <code class="inline"><span class="i">getpos</span><span class="s">(</span><span class="s">)</span></code>
.
Not yet supported.</p>
</li>
<li><a name="getpos-(-POS-)"></a><b>getpos ( POS )</b>
<p>Return the current position in the string, as an opaque object.
Not yet supported.</p>
</li>
</ul>
<a name="USING-THE-EXTERNAL-GZIP"></a><h1>USING THE EXTERNAL GZIP</h1>
<p>If the external <i>gzip</i> is used, the following <code class="inline"><a class="l_k" href="../functions/open.html">open</a></code>s are used:</p>
472
<pre class="verbatim"><ol><li>    <a class="l_k" href="../functions/open.html">open</a><span class="s">(</span><span class="w">FH</span><span class="cm">,</span> <span class="q">&quot;gzip -dc $filename |&quot;</span><span class="s">)</span>  <span class="c"># for read opens</span></li><li>    <a class="l_k" href="../functions/open.html">open</a><span class="s">(</span><span class="w">FH</span><span class="cm">,</span> <span class="q">&quot; | gzip &gt; $filename&quot;</span><span class="s">)</span>   <span class="c"># for write opens</span></li></ol></pre><p>You can modify the 'commands' for example to hardwire
473
an absolute path by e.g.</p>
474
<pre class="verbatim"><ol><li>    <a class="l_k" href="../functions/use.html">use</a> <span class="w">IO::Zlib</span> <span class="q">':gzip_read_open'</span>  <span class="cm">=&gt;</span> <span class="q">'/some/where/gunzip -c %s |'</span><span class="sc">;</span></li><li>    <a class="l_k" href="../functions/use.html">use</a> <span class="w">IO::Zlib</span> <span class="q">':gzip_write_open'</span> <span class="cm">=&gt;</span> <span class="q">'| /some/where/gzip.exe &gt; %s'</span><span class="sc">;</span></li></ol></pre><p>The <code class="inline"><span class="i">%s</span></code>
475 476
 is expanded to be the filename (<code class="inline"><a class="l_k" href="../functions/sprintf.html">sprintf</a></code> is used, so be
careful to escape any other <code class="inline"><span class="i">%</span></code>
477
 signs).  The 'commands' are checked
478 479 480 481 482 483 484 485 486
for sanity - they must contain the <code class="inline"><span class="i">%s</span></code>
, and the read open must end
with the pipe sign, and the write open must begin with the pipe sign.</p>
<a name="CLASS-METHODS"></a><h1>CLASS METHODS</h1>
<ul>
<li><a name="has_Compress_Zlib"></a><b>has_Compress_Zlib</b>
<p>Returns true if <code class="inline"><span class="w">Compress::Zlib</span></code>
 is available.  Note that this does
not mean that <code class="inline"><span class="w">Compress::Zlib</span></code>
487
 is being used: see <a href="#gzip_external">gzip_external</a>
488 489 490 491 492
and <a href="http://search.cpan.org/perldoc/gzip_used">gzip_used</a>.</p>
</li>
<li><a name="gzip_external"></a><b>gzip_external</b>
<p>Undef if an external <i>gzip</i> <b>can</b> be used if <code class="inline"><span class="w">Compress::Zlib</span></code>
 is
493
not available (see <a href="#has_Compress_Zlib">has_Compress_Zlib</a>), true if an external <i>gzip</i>
494
is explicitly used, false if an external <i>gzip</i> must not be used.
495
See <a href="#gzip_used">gzip_used</a>.</p>
496 497 498 499 500
</li>
<li><a name="gzip_used"></a><b>gzip_used</b>
<p>True if an external <i>gzip</i> is being used, false if not.</p>
</li>
<li><a name="gzip_read_open"></a><b>gzip_read_open</b>
501
<p>Return the 'command' being used for opening a file for reading using an
502 503 504
external <i>gzip</i>.</p>
</li>
<li><a name="gzip_write_open"></a><b>gzip_write_open</b>
505
<p>Return the 'command' being used for opening a file for writing using an
506 507 508 509 510 511 512 513
external <i>gzip</i>.</p>
</li>
</ul>
<a name="DIAGNOSTICS"></a><h1>DIAGNOSTICS</h1>
<ul>
<li><a name="IO%3a%3aZlib%3a%3agetlines%3a-must-be-called-in-list-context"></a><b>IO::Zlib::getlines: must be called in list context</b>
<p>If you want read lines, you must read in list context.</p>
</li>
514 515
<li><a name="IO%3a%3aZlib%3a%3agzopen_external%3a-mode-'...'-is-illegal"></a><b>IO::Zlib::gzopen_external: mode '...' is illegal</b>
<p>Use only modes 'rb' or 'wb' or /wb[1-9]/.</p>
516
</li>
517
<li><a name="IO%3a%3aZlib%3a%3aimport%3a-'...'-is-illegal"></a><b>IO::Zlib::import: '...' is illegal</b>
518 519 520 521 522 523
<p>The known import symbols are the <code class="inline"><span class="j">:</span><span class="w">gzip_external</span></code>
, <code class="inline"><span class="j">:</span><span class="w">gzip_read_open</span></code>
,
and <code class="inline"><span class="j">:</span><span class="w">gzip_write_open</span></code>
.  Anything else is not recognized.</p>
</li>
524
<li><a name="IO%3a%3aZlib%3a%3aimport%3a-'%3agzip_external'-requires-an-argument"></a><b>IO::Zlib::import: ':gzip_external' requires an argument</b>
525 526 527
<p>The <code class="inline"><span class="j">:</span><span class="w">gzip_external</span></code>
 requires one boolean argument.</p>
</li>
528
<li><a name="IO%3a%3aZlib%3a%3aimport%3a-'gzip_read_open'-requires-an-argument"></a><b>IO::Zlib::import: 'gzip_read_open' requires an argument</b>
529 530 531
<p>The <code class="inline"><span class="j">:</span><span class="w">gzip_external</span></code>
 requires one string argument.</p>
</li>
532
<li><a name="IO%3a%3aZlib%3a%3aimport%3a-'gzip_read'-'...'-is-illegal"></a><b>IO::Zlib::import: 'gzip_read' '...' is illegal</b>
533 534 535
<p>The <code class="inline"><span class="j">:</span><span class="w">gzip_read_open</span></code>
 argument must end with the pipe sign (|)
and have the <code class="inline"><span class="i">%s</span></code>
536
 for the filename.  See <a href="#USING-THE-EXTERNAL-GZIP">USING THE EXTERNAL GZIP</a>.</p>
537
</li>
538
<li><a name="IO%3a%3aZlib%3a%3aimport%3a-'gzip_write_open'-requires-an-argument"></a><b>IO::Zlib::import: 'gzip_write_open' requires an argument</b>
539 540 541
<p>The <code class="inline"><span class="j">:</span><span class="w">gzip_external</span></code>
 requires one string argument.</p>
</li>
542
<li><a name="IO%3a%3aZlib%3a%3aimport%3a-'gzip_write_open'-'...'-is-illegal"></a><b>IO::Zlib::import: 'gzip_write_open' '...' is illegal</b>
543 544 545 546 547
<p>The <code class="inline"><span class="j">:</span><span class="w">gzip_write_open</span></code>
 argument must begin with the pipe sign (|)
and have the <code class="inline"><span class="i">%s</span></code>
 for the filename.  An output redirect (&gt;) is also
often a good idea, depending on your operating system shell syntax.
548
See <a href="#USING-THE-EXTERNAL-GZIP">USING THE EXTERNAL GZIP</a>.</p>
549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566
</li>
<li><a name="IO%3a%3aZlib%3a%3aimport%3a-no-Compress%3a%3aZlib-and-no-external-gzip"></a><b>IO::Zlib::import: no Compress::Zlib and no external gzip</b>
<p>Given that we failed to load <code class="inline"><span class="w">Compress::Zlib</span></code>
 and that the use of
 an external <i>gzip</i> was disabled, IO::Zlib has not much chance of working.</p>
</li>
<li><a name="IO%3a%3aZlib%3a%3aopen%3a-needs-a-filename"></a><b>IO::Zlib::open: needs a filename</b>
<p>No filename, no open.</p>
</li>
<li><a name="IO%3a%3aZlib%3a%3aREAD%3a-NBYTES-must-be-specified"></a><b>IO::Zlib::READ: NBYTES must be specified</b>
<p>We must know how much to read.</p>
</li>
<li><a name="IO%3a%3aZlib%3a%3aWRITE%3a-too-long-LENGTH"></a><b>IO::Zlib::WRITE: too long LENGTH</b>
<p>The LENGTH must be less than or equal to the buffer size.</p>
</li>
</ul>
<a name="SEE-ALSO"></a><h1>SEE ALSO</h1>
<p><a href="../perlfunc.html">perlfunc</a>,
567
<a href="../perlop.html#I%2fO-Operators">I/O Operators in perlop</a>,
568 569 570 571 572 573 574 575 576
<a href="../IO/Handle.html">IO::Handle</a>,
<a href="../Compress/Zlib.html">Compress::Zlib</a></p>
<a name="HISTORY"></a><h1>HISTORY</h1>
<p>Created by Tom Hughes &lt;<i>tom@compton.nu</i>&gt;.</p>
<p>Support for external gzip added by Jarkko Hietaniemi &lt;<i>jhi@iki.fi</i>&gt;.</p>
<a name="COPYRIGHT"></a><h1>COPYRIGHT</h1>
<p>Copyright (c) 1998-2004 Tom Hughes &lt;<i>tom@compton.nu</i>&gt;.
All rights reserved. This program is free software; you can redistribute
it and/or modify it under the same terms as Perl itself.</p>
577 578 579 580




581 582 583 584 585
  <div id="page_index" class="hud_container">
    <div id="page_index_header" class="hud_header">
      <div id="page_index_close" class="hud_close"><a href="#" onClick="pageIndex.hide();return false;"></a></div>
      <div id="page_index_title" class="hud_title"><span class="hud_span_top">Page index</span></div>
      <div id="page_index_topright" class="hud_topright"></div>
586
    </div>
587
    <div id="page_index_content" class="hud_content">
588 589
      <ul><li><a href="#NAME">NAME</a><li><a href="#SYNOPSIS">SYNOPSIS</a><li><a href="#DESCRIPTION">DESCRIPTION</a><li><a href="#CONSTRUCTOR">CONSTRUCTOR</a><li><a href="#OBJECT-METHODS">OBJECT METHODS</a><li><a href="#USING-THE-EXTERNAL-GZIP">USING THE EXTERNAL GZIP</a><li><a href="#CLASS-METHODS">CLASS METHODS</a><li><a href="#DIAGNOSTICS">DIAGNOSTICS</a><li><a href="#SEE-ALSO">SEE ALSO</a><li><a href="#HISTORY">HISTORY</a><li><a href="#COPYRIGHT">COPYRIGHT</a></ul>
    </div>
590 591 592 593
    <div id="page_index_footer" class="hud_footer">
      <div id="page_index_bottomleft" class="hud_bottomleft"></div>
      <div id="page_index_bottom" class="hud_bottom"><span class="hud_span_bottom"></span></div>
      <div id="page_index_resize" class="hud_resize"></div>
594 595 596
    </div>
  </div>

597 598 599 600 601 602 603

	    &nbsp;
          </div>
          <div id="content_footer">
          </div>
        </div>
        <div class="clear"></div>
604
      </div>
605
      
606 607 608 609 610 611 612 613 614
    <div id="footer">
      <div id="footer_content">
        <div id="footer_strapline">
          perldoc.perl.org - Official documentation for the Perl programming language
        </div>
        <div id="footer_links">
          <div id="address">
            <p class="name">Contact details</p>
            <p class="address">
615
	      Site maintained by <a href="mailto:jj@jonallen.info">Jon Allen (JJ)</a><br>
616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651
	    </p>
            <p class="contact">
              Documentation maintained by the <a href="http://lists.cpan.org/showlist.cgi?name=perl5-porters">Perl 5 Porters</a>
            </p>
          </div>
          <ul class="f1">
            <li>Manual
              <ul class="f2">
                <li><a href="../index-overview.html">Overview</a>
                <li><a href="../index-tutorials.html">Tutorials</a>
                <li><a href="../index-faq.html">FAQs</a>
                <li><a href="../index-history.html">Changes</a>
              </ul>
            <li>Reference
              <ul class="f2">
                <li><a href="../index-language.html">Language</a>
                <li><a href="../index-functions.html">Functions</a>
                <li><a href="../perlop.html">Operators</a>
                <li><a href="../perlvar.html">Variables</a>
              </ul>
            <li>Modules
              <ul class="f2">
                <li><a href="../index-modules-A.html">Modules</a>
                <li><a href="../index-pragmas.html">Pragmas</a>
                <li><a href="../index-utilities.html">Utilities</a>
              </ul>
            <li>Misc
              <ul class="f2">
                <li><a href="../index-licence.html">License</a>
                <li><a href="../index-internals.html">Internals</a>
                <li><a href="../index-platforms.html">Platforms</a>
              </ul>          </ul>
          <div class="clear"></div>
        </div>
      </div>
      <div id="footer_end">
652
      </div>
653
    </div>
654
      
655
    </div>
656 657
      <script language="JavaScript" type="text/javascript" src="../static/exploreperl.js"></script>
      <script language="JavaScript" src="../static/combined-20100403.js" type="text/javascript"></script>
658 659 660 661 662
<script language="JavaScript" type="text/javascript">
  perldoc.setPath(1);
  perldoc.pageName    = 'IO::Zlib';
  perldoc.pageAddress = 'IO/Zlib.html';
  perldoc.contentPage = 1;
663 664
  explorePerl.render();
  explorePerl.addEvents('explore_anchor');
665 666 667
</script>
    
  </body>
668
</html>