1<?xml version="1.0" encoding="ISO-8859-1"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head><!-- 4 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 5 This file is generated from xml source: DO NOT EDIT 6 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 7 --> 8<title>Apache Tutorial: Dynamic Content with CGI - Apache HTTP Server</title> 9<link href="/style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" /> 10<link href="/style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" /> 11<link href="/style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" /><link rel="stylesheet" type="text/css" href="/style/css/prettify.css" /> 12<script src="/style/scripts/prettify.js" type="text/javascript"> 13</script> 14 15<link href="/images/favicon.ico" rel="shortcut icon" /></head> 16<body id="manual-page"><div id="page-header"> 17<p class="menu"><a href="/mod/">Modules</a> | <a href="/mod/directives.html">Directives</a> | <a href="http://wiki.apache.org/httpd/FAQ">FAQ</a> | <a href="/glossary.html">Glossary</a> | <a href="/sitemap.html">Sitemap</a></p> 18<p class="apache">Apache HTTP Server Version 2.2</p> 19<img alt="" src="/images/feather.gif" /></div> 20<div class="up"><a href="./"><img title="<-" alt="<-" src="/images/left.gif" /></a></div> 21<div id="path"> 22<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="../">Version 2.2</a> > <a href="./">How-To / Tutorials</a></div><div id="page-content"><div id="preamble"><h1>Apache Tutorial: Dynamic Content with CGI</h1> 23<div class="toplang"> 24<p><span>Available Languages: </span><a href="/en/howto/cgi.html" title="English"> en </a> | 25<a href="/ja/howto/cgi.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> | 26<a href="/ko/howto/cgi.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p> 27</div> 28</div> 29<div id="quickview"><ul id="toc"><li><img alt="" src="/images/down.gif" /> <a href="#intro">Introduction</a></li> 30<li><img alt="" src="/images/down.gif" /> <a href="#configuring">Configuring Apache to permit CGI</a></li> 31<li><img alt="" src="/images/down.gif" /> <a href="#writing">Writing a CGI program</a></li> 32<li><img alt="" src="/images/down.gif" /> <a href="#troubleshoot">But it's still not working!</a></li> 33<li><img alt="" src="/images/down.gif" /> <a href="#behindscenes">What's going on behind the scenes?</a></li> 34<li><img alt="" src="/images/down.gif" /> <a href="#libraries">CGI modules/libraries</a></li> 35<li><img alt="" src="/images/down.gif" /> <a href="#moreinfo">For more information</a></li> 36</ul><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div> 37<div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 38<div class="section"> 39<h2><a name="intro" id="intro">Introduction</a></h2> 40 41 42 <table class="related"><tr><th>Related Modules</th><th>Related Directives</th></tr><tr><td><ul><li><code class="module"><a href="/mod/mod_alias.html">mod_alias</a></code></li><li><code class="module"><a href="/mod/mod_cgi.html">mod_cgi</a></code></li></ul></td><td><ul><li><code class="directive"><a href="/mod/mod_mime.html#addhandler">AddHandler</a></code></li><li><code class="directive"><a href="/mod/core.html#options">Options</a></code></li><li><code class="directive"><a href="/mod/mod_alias.html#scriptalias">ScriptAlias</a></code></li></ul></td></tr></table> 43 44 <p>The CGI (Common Gateway Interface) defines a way for a web 45 server to interact with external content-generating programs, 46 which are often referred to as CGI programs or CGI scripts. It 47 is the simplest, and most common, way to put dynamic content on 48 your web site. This document will be an introduction to setting 49 up CGI on your Apache web server, and getting started writing 50 CGI programs.</p> 51 </div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 52<div class="section"> 53<h2><a name="configuring" id="configuring">Configuring Apache to permit CGI</a></h2> 54 55 56 <p>In order to get your CGI programs to work properly, you'll 57 need to have Apache configured to permit CGI execution. There 58 are several ways to do this.</p> 59 60 <div class="warning">Note: If Apache has been built with shared module 61 support you need to ensure that the module is loaded; in your 62 <code>httpd.conf</code> you need to make sure the 63 <code class="directive"><a href="/mod/mod_so.html#loadmodule">LoadModule</a></code> 64 directive has not been commented out. A correctly configured directive 65 may look like this: 66 67 <pre class="prettyprint lang-config"> 68 LoadModule cgi_module modules/mod_cgi.so 69 </pre> 70</div> 71 72 <h3><a name="scriptalias" id="scriptalias">ScriptAlias</a></h3> 73 74 75 <p>The 76 <code class="directive"><a href="/mod/mod_alias.html#scriptalias">ScriptAlias</a></code> 77 78 directive tells Apache that a particular directory is set 79 aside for CGI programs. Apache will assume that every file in 80 this directory is a CGI program, and will attempt to execute 81 it, when that particular resource is requested by a 82 client.</p> 83 84 <p>The <code class="directive"><a href="/mod/mod_alias.html#scriptalias">ScriptAlias</a></code> 85 directive looks like:</p> 86 87 <div class="example"><p><code> 88 ScriptAlias /cgi-bin/ /usr/local/apache2/cgi-bin/ 89 </code></p></div> 90 91 <p>The example shown is from your default <code>httpd.conf</code> 92 configuration file, if you installed Apache in the default 93 location. The <code class="directive"><a href="/mod/mod_alias.html#scriptalias">ScriptAlias</a></code> 94 directive is much like the <code class="directive"><a href="/mod/mod_alias.html#alias">Alias</a></code> directive, which defines a URL prefix that 95 is to mapped to a particular directory. <code class="directive">Alias</code> 96 and <code class="directive">ScriptAlias</code> are usually used for 97 directories that are outside of the <code class="directive"><a href="/mod/core.html#documentroot">DocumentRoot</a></code> directory. The difference between 98 <code class="directive">Alias</code> and <code class="directive">ScriptAlias</code> 99 is that <code class="directive">ScriptAlias</code> has the added meaning 100 that everything under that URL prefix will be considered a CGI 101 program. So, the example above tells Apache that any request for a 102 resource beginning with <code>/cgi-bin/</code> should be served from 103 the directory <code>/usr/local/apache2/cgi-bin/</code>, and should be 104 treated as a CGI program.</p> 105 106 <p>For example, if the URL 107 <code>http://www.example.com/cgi-bin/test.pl</code> 108 is requested, Apache will attempt to execute the file 109 <code>/usr/local/apache2/cgi-bin/test.pl</code> 110 and return the output. Of course, the file will have to 111 exist, and be executable, and return output in a particular 112 way, or Apache will return an error message.</p> 113 114 115 <h3><a name="nonscriptalias" id="nonscriptalias">CGI outside of ScriptAlias directories</a></h3> 116 117 118 <p>CGI programs are often restricted to <code class="directive"><a href="/mod/mod_alias.html#scriptalias">ScriptAlias</a></code>'ed directories for security reasons. 119 In this way, administrators can tightly control who is allowed to 120 use CGI programs. However, if the proper security precautions are 121 taken, there is no reason why CGI programs cannot be run from 122 arbitrary directories. For example, you may wish to let users 123 have web content in their home directories with the 124 <code class="directive"><a href="/mod/mod_userdir.html#userdir">UserDir</a></code> directive. 125 If they want to have their own CGI programs, but don't have access to 126 the main <code>cgi-bin</code> directory, they will need to be able to 127 run CGI programs elsewhere.</p> 128 129 <p>There are two steps to allowing CGI execution in an arbitrary 130 directory. First, the <code>cgi-script</code> handler must be 131 activated using the <code class="directive"><a href="/mod/mod_mime.html#addhandler">AddHandler</a></code> or <code class="directive"><a href="/mod/core.html#sethandler">SetHandler</a></code> directive. Second, 132 <code>ExecCGI</code> must be specified in the <code class="directive"><a href="/mod/core.html#options">Options</a></code> directive.</p> 133 134 135 <h3><a name="options" id="options">Explicitly using Options to permit CGI execution</a></h3> 136 137 138 <p>You could explicitly use the <code class="directive"><a href="/mod/core.html#options">Options</a></code> directive, inside your main server configuration 139 file, to specify that CGI execution was permitted in a particular 140 directory:</p> 141 142 <div class="example"><p><code> 143 <Directory /usr/local/apache2/htdocs/somedir><br /> 144 <span class="indent"> 145 Options +ExecCGI<br /> 146 </span> 147</Directory> 148 </code></p></div> 149 150 <p>The above directive tells Apache to permit the execution 151 of CGI files. You will also need to tell the server what 152 files are CGI files. The following <code class="directive"><a href="/mod/mod_mime.html#addhandler">AddHandler</a></code> directive tells the server to treat all 153 files with the <code>cgi</code> or <code>pl</code> extension as CGI 154 programs:</p> 155 156 <div class="example"><p><code> 157 AddHandler cgi-script .cgi .pl 158 </code></p></div> 159 160 161 <h3><a name="htaccess" id="htaccess">.htaccess files</a></h3> 162 163 164 <p>The <a href="htaccess.html"><code>.htaccess</code> tutorial</a> 165 shows how to activate CGI programs if you do not have 166 access to <code>httpd.conf</code>.</p> 167 168 169 <h3><a name="userdir" id="userdir">User Directories</a></h3> 170 171 172 <p>To allow CGI program execution for any file ending in 173 <code>.cgi</code> in users' directories, you can use the 174 following configuration.</p> 175 176 <div class="example"><p><code> 177 <Directory /home/*/public_html><br /> 178 <span class="indent"> 179 Options +ExecCGI<br /> 180 AddHandler cgi-script .cgi<br /> 181 </span> 182</Directory> 183 </code></p></div> 184 185 <p>If you wish designate a <code>cgi-bin</code> subdirectory of 186 a user's directory where everything will be treated as a CGI 187 program, you can use the following.</p> 188 189 <div class="example"><p><code> 190 <Directory /home/*/public_html/cgi-bin><br /> 191 <span class="indent"> 192 Options ExecCGI<br /> 193 SetHandler cgi-script<br /> 194 </span> 195</Directory> 196 </code></p></div> 197 198 199 200 </div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 201<div class="section"> 202<h2><a name="writing" id="writing">Writing a CGI program</a></h2> 203 204 205 <p>There are two main differences between ``regular'' 206 programming, and CGI programming.</p> 207 208 <p>First, all output from your CGI program must be preceded by 209 a <a class="glossarylink" href="/glossary.html#mime-type" title="see glossary">MIME-type</a> header. This is HTTP header that tells the client 210 what sort of content it is receiving. Most of the time, this 211 will look like:</p> 212 213 <div class="example"><p><code> 214 Content-type: text/html 215 </code></p></div> 216 217 <p>Secondly, your output needs to be in HTML, or some other 218 format that a browser will be able to display. Most of the 219 time, this will be HTML, but occasionally you might write a CGI 220 program that outputs a gif image, or other non-HTML 221 content.</p> 222 223 <p>Apart from those two things, writing a CGI program will look 224 a lot like any other program that you might write.</p> 225 226 <h3><a name="firstcgi" id="firstcgi">Your first CGI program</a></h3> 227 228 229 <p>The following is an example CGI program that prints one 230 line to your browser. Type in the following, save it to a 231 file called <code>first.pl</code>, and put it in your 232 <code>cgi-bin</code> directory.</p> 233 234 <div class="example"><p><code> 235 #!/usr/bin/perl<br /> 236 print "Content-type: text/html\n\n";<br /> 237print "Hello, World."; 238 </code></p></div> 239 240 <p>Even if you are not familiar with Perl, you should be able 241 to see what is happening here. The first line tells Apache 242 (or whatever shell you happen to be running under) that this 243 program can be executed by feeding the file to the 244 interpreter found at the location <code>/usr/bin/perl</code>. 245 The second line prints the content-type declaration we 246 talked about, followed by two carriage-return newline pairs. 247 This puts a blank line after the header, to indicate the end 248 of the HTTP headers, and the beginning of the body. The third 249 line prints the string "Hello, World.". And that's the end 250 of it.</p> 251 252 <p>If you open your favorite browser and tell it to get the 253 address</p> 254 255 <div class="example"><p><code> 256 http://www.example.com/cgi-bin/first.pl 257 </code></p></div> 258 259 <p>or wherever you put your file, you will see the one line 260 <code>Hello, World.</code> appear in your browser window. 261 It's not very exciting, but once you get that working, you'll 262 have a good chance of getting just about anything working.</p> 263 264 </div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 265<div class="section"> 266<h2><a name="troubleshoot" id="troubleshoot">But it's still not working!</a></h2> 267 268 269 <p>There are four basic things that you may see in your browser 270 when you try to access your CGI program from the web:</p> 271 272 <dl> 273 <dt>The output of your CGI program</dt> 274 <dd>Great! That means everything worked fine. If the output is correct, 275 but the browser is not processing it correctly, make sure you have the 276 correct <code>Content-Type</code> set in your CGI program.</dd> 277 278 <dt>The source code of your CGI program or a "POST Method Not 279 Allowed" message</dt> 280 <dd>That means that you have not properly configured Apache 281 to process your CGI program. Reread the section on 282 <a href="#configuring">configuring 283 Apache</a> and try to find what you missed.</dd> 284 285 <dt>A message starting with "Forbidden"</dt> 286 <dd>That means that there is a permissions problem. Check the 287 <a href="#errorlogs">Apache error log</a> and the section below on 288 <a href="#permissions">file permissions</a>.</dd> 289 290 <dt>A message saying "Internal Server Error"</dt> 291 <dd>If you check the 292 <a href="#errorlogs">Apache error log</a>, you will probably 293 find that it says "Premature end of 294 script headers", possibly along with an error message 295 generated by your CGI program. In this case, you will want to 296 check each of the below sections to see what might be 297 preventing your CGI program from emitting the proper HTTP 298 headers.</dd> 299 </dl> 300 301 <h3><a name="permissions" id="permissions">File permissions</a></h3> 302 303 304 <p>Remember that the server does not run as you. That is, 305 when the server starts up, it is running with the permissions 306 of an unprivileged user - usually <code>nobody</code>, or 307 <code>www</code> - and so it will need extra permissions to 308 execute files that are owned by you. Usually, the way to give 309 a file sufficient permissions to be executed by <code>nobody</code> 310 is to give everyone execute permission on the file:</p> 311 312 <div class="example"><p><code> 313 chmod a+x first.pl 314 </code></p></div> 315 316 <p>Also, if your program reads from, or writes to, any other 317 files, those files will need to have the correct permissions 318 to permit this.</p> 319 320 321 322 <h3><a name="pathinformation" id="pathinformation">Path information and environment</a></h3> 323 324 325 <p>When you run a program from your command line, you have 326 certain information that is passed to the shell without you 327 thinking about it. For example, you have a <code>PATH</code>, 328 which tells the shell where it can look for files that you 329 reference.</p> 330 331 <p>When a program runs through the web server as a CGI program, 332 it may not have the same <code>PATH</code>. Any programs that you 333 invoke in your CGI program (like <code>sendmail</code>, for 334 example) will need to be specified by a full path, so that the 335 shell can find them when it attempts to execute your CGI 336 program.</p> 337 338 <p>A common manifestation of this is the path to the script 339 interpreter (often <code>perl</code>) indicated in the first 340 line of your CGI program, which will look something like:</p> 341 342 <div class="example"><p><code> 343 #!/usr/bin/perl 344 </code></p></div> 345 346 <p>Make sure that this is in fact the path to the 347 interpreter.</p> 348 <div class="warning"> 349 When editing CGI scripts on Windows, end-of-line characters may be 350 appended to the interpreter path. Ensure that files are then 351 transferred to the server in ASCII mode. Failure to do so may 352 result in "Command not found" warnings from the OS, due to the 353 unrecognized end-of-line character being interpreted as a part of 354 the interpreter filename. 355 </div> 356 357 358 <h3><a name="missingenv" id="missingenv">Missing environment variables</a></h3> 359 360 361 <p>If your CGI program depends on non-standard <a href="#env">environment variables</a>, you will need to 362 assure that those variables are passed by Apache.</p> 363 364 <p>When you miss HTTP headers from the environment, make 365 sure they are formatted according to 366 <a href="http://tools.ietf.org/html/rfc2616">RFC 2616</a>, 367 section 4.2: Header names must start with a letter, 368 followed only by letters, numbers or hyphen. Any header 369 violating this rule will be dropped silently.</p> 370 371 372 373 <h3><a name="syntaxerrors" id="syntaxerrors">Program errors</a></h3> 374 375 376 <p>Most of the time when a CGI program fails, it's because of 377 a problem with the program itself. This is particularly true 378 once you get the hang of this CGI stuff, and no longer make 379 the above two mistakes. The first thing to do is to make 380 sure that your program runs from the command line before 381 testing it via the web server. For example, try:</p> 382 383 <div class="example"><p><code> 384 cd /usr/local/apache2/cgi-bin<br /> 385 /first.pl 386 </code></p></div> 387 388 <p>(Do not call the <code>perl</code> interpreter. The shell 389 and Apache should find the interpreter using the <a href="#pathinformation">path information</a> on the first line of 390 the script.)</p> 391 392 <p>The first thing you see written by your program should be 393 a set of HTTP headers, including the <code>Content-Type</code>, 394 followed by a blank line. If you see anything else, Apache will 395 return the <code>Premature end of script headers</code> error if 396 you try to run it through the server. See <a href="#writing">Writing a CGI program</a> above for more 397 details.</p> 398 399 400 <h3><a name="errorlogs" id="errorlogs">Error logs</a></h3> 401 402 403 <p>The error logs are your friend. Anything that goes wrong 404 generates message in the error log. You should always look 405 there first. If the place where you are hosting your web site 406 does not permit you access to the error log, you should 407 probably host your site somewhere else. Learn to read the 408 error logs, and you'll find that almost all of your problems 409 are quickly identified, and quickly solved.</p> 410 411 412 <h3><a name="suexec" id="suexec">Suexec</a></h3> 413 414 415 <p>The <a href="/suexec.html">suexec</a> support program 416 allows CGI programs to be run under different user permissions, 417 depending on which virtual host or user home directory they are 418 located in. Suexec has very strict permission checking, and any 419 failure in that checking will result in your CGI programs 420 failing with <code>Premature end of script headers</code>.</p> 421 422 <p>To check if you are using suexec, run <code>apachectl 423 -V</code> and check for the location of <code>SUEXEC_BIN</code>. 424 If Apache finds an <code class="program"><a href="/programs/suexec.html">suexec</a></code> binary there on startup, 425 suexec will be activated.</p> 426 427 <p>Unless you fully understand suexec, you should not be using it. 428 To disable suexec, simply remove (or rename) the <code class="program"><a href="/programs/suexec.html">suexec</a></code> 429 binary pointed to by <code>SUEXEC_BIN</code> and then restart the 430 server. If, after reading about <a href="/suexec.html">suexec</a>, 431 you still wish to use it, then run <code>suexec -V</code> to find 432 the location of the suexec log file, and use that log file to 433 find what policy you are violating.</p> 434 435 </div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 436<div class="section"> 437<h2><a name="behindscenes" id="behindscenes">What's going on behind the scenes?</a></h2> 438 439 440 <p>As you become more advanced in CGI programming, it will 441 become useful to understand more about what's happening behind 442 the scenes. Specifically, how the browser and server 443 communicate with one another. Because although it's all very 444 well to write a program that prints "Hello, World.", it's not 445 particularly useful.</p> 446 447 <h3><a name="env" id="env">Environment variables</a></h3> 448 449 450 <p>Environment variables are values that float around you as 451 you use your computer. They are useful things like your path 452 (where the computer searches for the actual file 453 implementing a command when you type it), your username, your 454 terminal type, and so on. For a full list of your normal, 455 every day environment variables, type 456 <code>env</code> at a command prompt.</p> 457 458 <p>During the CGI transaction, the server and the browser 459 also set environment variables, so that they can communicate 460 with one another. These are things like the browser type 461 (Netscape, IE, Lynx), the server type (Apache, IIS, WebSite), 462 the name of the CGI program that is being run, and so on.</p> 463 464 <p>These variables are available to the CGI programmer, and 465 are half of the story of the client-server communication. The 466 complete list of required variables is at 467 <a href="http://www.ietf.org/rfc/rfc3875">Common Gateway 468 Interface RFC</a>.</p> 469 470 <p>This simple Perl CGI program will display all of the 471 environment variables that are being passed around. Two 472 similar programs are included in the 473 <code>cgi-bin</code> 474 475 directory of the Apache distribution. Note that some 476 variables are required, while others are optional, so you may 477 see some variables listed that were not in the official list. 478 In addition, Apache provides many different ways for you to 479 <a href="/env.html">add your own environment variables</a> 480 to the basic ones provided by default.</p> 481 482 <div class="example"><p><code> 483 #!/usr/bin/perl<br /> 484 print "Content-type: text/html\n\n";<br /> 485 foreach $key (keys %ENV) {<br /> 486 <span class="indent"> 487 print "$key --> $ENV{$key}<br>";<br /> 488 </span> 489} 490 </code></p></div> 491 492 493 <h3><a name="stdin" id="stdin">STDIN and STDOUT</a></h3> 494 495 496 <p>Other communication between the server and the client 497 happens over standard input (<code>STDIN</code>) and standard 498 output (<code>STDOUT</code>). In normal everyday context, 499 <code>STDIN</code> means the keyboard, or a file that a 500 program is given to act on, and <code>STDOUT</code> 501 usually means the console or screen.</p> 502 503 <p>When you <code>POST</code> a web form to a CGI program, 504 the data in that form is bundled up into a special format 505 and gets delivered to your CGI program over <code>STDIN</code>. 506 The program then can process that data as though it was 507 coming in from the keyboard, or from a file</p> 508 509 <p>The "special format" is very simple. A field name and 510 its value are joined together with an equals (=) sign, and 511 pairs of values are joined together with an ampersand 512 (&). Inconvenient characters like spaces, ampersands, and 513 equals signs, are converted into their hex equivalent so that 514 they don't gum up the works. The whole data string might look 515 something like:</p> 516 517 <div class="example"><p><code> 518 name=Rich%20Bowen&city=Lexington&state=KY&sidekick=Squirrel%20Monkey 519 </code></p></div> 520 521 <p>You'll sometimes also see this type of string appended to 522 a URL. When that is done, the server puts that string 523 into the environment variable called 524 <code>QUERY_STRING</code>. That's called a <code>GET</code> 525 request. Your HTML form specifies whether a <code>GET</code> 526 or a <code>POST</code> is used to deliver the data, by setting the 527 <code>METHOD</code> attribute in the <code>FORM</code> tag.</p> 528 529 <p>Your program is then responsible for splitting that string 530 up into useful information. Fortunately, there are libraries 531 and modules available to help you process this data, as well 532 as handle other of the aspects of your CGI program.</p> 533 534 </div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 535<div class="section"> 536<h2><a name="libraries" id="libraries">CGI modules/libraries</a></h2> 537 538 539 <p>When you write CGI programs, you should consider using a 540 code library, or module, to do most of the grunt work for you. 541 This leads to fewer errors, and faster development.</p> 542 543 <p>If you're writing CGI programs in Perl, modules are 544 available on <a href="http://www.cpan.org/">CPAN</a>. The most 545 popular module for this purpose is <code>CGI.pm</code>. You might 546 also consider <code>CGI::Lite</code>, which implements a minimal 547 set of functionality, which is all you need in most programs.</p> 548 549 <p>If you're writing CGI programs in C, there are a variety of 550 options. One of these is the <code>CGIC</code> library, from 551 <a href="http://www.boutell.com/cgic/">http://www.boutell.com/cgic/</a>.</p> 552 </div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div> 553<div class="section"> 554<h2><a name="moreinfo" id="moreinfo">For more information</a></h2> 555 556 557 <p>There are a large number of CGI resources on the web. 558 The list from the HTML Writers Guild is a great source of answers 559 to your questions. You can find out more at 560 <a href="http://www.hwg.org/lists/hwg-servers/">http://www.hwg.org/lists/hwg-servers/</a>.</p> 561 562 <p>The current CGI specification is available in the 563 <a href="http://www.ietf.org/rfc/rfc3875">Common Gateway 564 Interface RFC</a>.</p> 565 566 <p>When you post a question about a CGI problem that you're 567 having, whether to a mailing list, or to a newsgroup, make sure 568 you provide enough information about what happened, what you 569 expected to happen, and how what actually happened was 570 different, what server you're running, what language your CGI 571 program was in, and, if possible, the offending code. This will 572 make finding your problem much simpler.</p> 573 574 <p>Note that questions about CGI problems should <strong>never</strong> 575 be posted to the Apache bug database unless you are sure you 576 have found a problem in the Apache source code.</p> 577 </div></div> 578<div class="bottomlang"> 579<p><span>Available Languages: </span><a href="/en/howto/cgi.html" title="English"> en </a> | 580<a href="/ja/howto/cgi.html" hreflang="ja" rel="alternate" title="Japanese"> ja </a> | 581<a href="/ko/howto/cgi.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p> 582</div><div class="top"><a href="#page-header"><img src="/images/up.gif" alt="top" /></a></div><div class="section"><h2><a id="comments_section" name="comments_section">Comments</a></h2><div class="warning"><strong>Notice:</strong><br />This is not a Q&A section. 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