<?xml version="1.0" encoding="utf-8"?><indexterm id="INDEX-1" file="ch01_01.htm" sect="1. Getting Started "><primary>CGI (Common GatewayInterface)</primary></indexterm><indexterm id="INDEX-2" file="ch01_01.htm" sect="1. Getting Started "><primary>CGI (CommonGatewayInterface)</primary><secondary>applications</secondary><see>programs,CGI</see></indexterm><indexterm id="INDEX-3" file="ch01_01.htm" sect="1.1. History"><primary>Internet, historyof</primary></indexterm><indexterm id="INDEX-4" file="ch01_01.htm" sect="1.1. History"><primary>CGI (Common GatewayInterface)</primary><secondary>history</secondary></indexterm><indexterm id="INDEX-5" file="ch01_01.htm" sect="1.1. History"><primary>web, historyof</primary></indexterm><indexterm id="INDEX-6" file="ch01_01.htm" sect="1.1. History"><primary>URLs (Uniform ResourceLocators)</primary></indexterm><indexterm id="INDEX-7" file="ch01_01.htm" sect="1.1.1. How CGI Is Used Today"><primary>e-commerce</primary></indexterm><indexterm id="INDEX-8" file="ch01_01.htm" sect="1.1.1. How CGI Is Used Today"><primary>CGI (Common GatewayInterface)</primary><secondary>e-commerce, usein</secondary></indexterm><indexterm id="INDEX-9" file="ch01_01.htm" sect="1.1.1. How CGI Is Used Today"><primary>static vs. dynamicresources</primary></indexterm><indexterm id="INDEX-10" file="ch01_01.htm" sect="1.1.1. How CGI Is Used Today"><primary>dynamicresources, CGI support of</primary></indexterm><indexterm id="INDEX-11" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>cgi-bin directory</primary></indexterm><indexterm id="INDEX-12" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>web servers</primary><secondary>cgi-bindiretory</secondary></indexterm><indexterm id="INDEX-13" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>STDIN (standardinput)</primary></indexterm><indexterm id="INDEX-14" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>environment variables</primary></indexterm><indexterm id="INDEX-15" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>Unix operatingsystem</primary><secondary>variables</secondary><see>environmentvariables</see></indexterm><indexterm id="INDEX-16" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>variables</primary><seealso sortas="zzzsee also">environment variables</seealso></indexterm><indexterm id="INDEX-17" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>STDOUT (standardoutput)</primary></indexterm><indexterm id="INDEX-18" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>standardoutput</primary><see>output STDOUT</see></indexterm><indexterm id="INDEX-19" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>standard input</primary><see>inputSTDIN</see></indexterm><indexterm id="INDEX-20" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>Perl language</primary><secondary>printing,STDOUT and</secondary></indexterm><indexterm id="INDEX-21" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>printing</primary><secondary sortas="STDOUT">toSTDOUT</secondary></indexterm><indexterm id="INDEX-22" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>programs,CGI</primary><secondary>HTTP header lines,returning</secondary></indexterm><indexterm id="INDEX-23" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>headers</primary><secondary>HTTP</secondary><tertiary>formattinginformation in</tertiary></indexterm><indexterm id="INDEX-24" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>responses, HTTP</primary></indexterm><indexterm id="INDEX-25" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>web browsers</primary><secondary>response fromweb server (example)</secondary></indexterm><indexterm id="INDEX-26" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>webservers</primary><secondary>response to web browser(example)</secondary></indexterm><indexterm id="INDEX-27" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>headers</primary><secondary>information in,web server response</secondary></indexterm><indexterm id="INDEX-28" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>protocols</primary><secondary>header (web serverresponse), listing in</secondary></indexterm><indexterm id="INDEX-29" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>media types</primary></indexterm><indexterm id="INDEX-30" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>documents</primary><secondary>mediatypes</secondary><tertiary>listing in web server responseheader</tertiary></indexterm><indexterm id="INDEX-31" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>programs,CGI</primary><secondary>dynamic generation of web serverresponse</secondary></indexterm><indexterm id="INDEX-32" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>staticdocuments</primary><secondary>HTML</secondary><tertiary>for webserver response</tertiary></indexterm><indexterm id="INDEX-33" file="ch01_02.htm" sect="1.2. Introduction to CGI"><primary>CGI(Common GatewayInterface)</primary><secondary>scripts</secondary><see>programs,CGI</see></indexterm><indexterm id="INDEX-34" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>programs,CGI</primary><secondary>application(example)</secondary></indexterm><indexterm id="INDEX-35" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>HTML (Hypertext MarkupLanguage)</primary><secondary>documents</secondary><tertiary>CGIapplication, generating with</tertiary></indexterm><indexterm id="INDEX-36" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>commands</primary></indexterm><indexterm id="INDEX-37" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>-wTflags</primary></indexterm><indexterm id="INDEX-38" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>Perllanguage</primary><secondary>turning on warnings and taintchecking</secondary></indexterm><indexterm id="INDEX-39" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>warnings</primary><secondary>turning on inperl</secondary></indexterm><indexterm id="INDEX-40" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>taint checking,turning on in perl</primary></indexterm><indexterm id="INDEX-41" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>flags</primary><secondary>taint andwarning</secondary></indexterm><indexterm id="INDEX-42" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>use strictcommand</primary></indexterm><indexterm id="INDEX-43" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>strictmode</primary></indexterm><indexterm id="INDEX-44" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>variables</primary><secondary>strict rules for,using</secondary></indexterm><indexterm id="INDEX-45" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>subroutines</primary><secondary>strict rules for,using</secondary></indexterm><indexterm id="INDEX-46" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>references</primary><secondary>strict rules for,using</secondary></indexterm><indexterm id="INDEX-47" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>programs, CGI</primary><secondary>strict command,advantages of use</secondary></indexterm><indexterm id="INDEX-48" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>variables</primary><secondary>declaring andreducing number of global</secondary></indexterm><indexterm id="INDEX-49" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>global variables</primary><secondary>reducingnumber of with strict pragma</secondary></indexterm><indexterm id="INDEX-50" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>FastCGI</primary><secondary>strict pragma,required use of</secondary></indexterm><indexterm id="INDEX-51" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>mod_perl</primary><secondary>strict pragma,required use of</secondary></indexterm><indexterm id="INDEX-52" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>environment variables</primary><secondary>CGIscripts</secondary><tertiary>examples of</tertiary></indexterm><indexterm id="INDEX-53" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>programs, CGI</primary><secondary>environmentvariables</secondary><tertiary>examples</tertiary></indexterm><indexterm id="INDEX-54" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>domain names</primary><secondary>remote machine,obtaining from environment variables</secondary></indexterm><indexterm id="INDEX-55" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>IP (InternetProtocol)</primary><secondary>addresses</secondary><tertiary>remotehost, obtaining from environment variables</tertiary></indexterm><indexterm id="INDEX-56" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>headers</primary><secondary>HTTP</secondary><tertiary>CGIscripts, declaring type of document output</tertiary></indexterm><indexterm id="INDEX-57" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>documents</primary><secondary>mediatypes</secondary><tertiary>declaring in HTTPheaders</tertiary></indexterm><indexterm id="INDEX-58" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>printstatements</primary><secondary>here documents</secondary></indexterm><indexterm id="INDEX-59" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>here documents</primary><secondary>printstatements</secondary></indexterm><indexterm id="INDEX-60" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>double quotes</primary><secondary>enclosing"here" documents in</secondary></indexterm><indexterm id="INDEX-61" file="ch01_02.htm" sect="1.2.1. Sample CGI"><primary>double quotes</primary><seealso sortas="zzzsee also">quotes; single quotes</seealso></indexterm><indexterm id="INDEX-62" file="ch01_02.htm" sect="1.2.2. Invoking CGI Scripts"><primary>programs, CGI</primary><secondary>URLsfor</secondary></indexterm><indexterm id="INDEX-63" file="ch01_02.htm" sect="1.2.2. Invoking CGI Scripts"><primary>webservers</primary><secondary>CGI scripts</secondary><tertiary>mappingvirtual directory to</tertiary></indexterm><indexterm id="INDEX-64" file="ch01_02.htm" sect="1.2.2. Invoking CGI Scripts"><primary>invoking CGI scripts</primary></indexterm><indexterm id="INDEX-65" file="ch01_02.htm" sect="1.2.2. Invoking CGI Scripts"><primary>URLs (Uniform ResourceLocators)</primary><secondary>CGI scripts</secondary></indexterm><indexterm id="INDEX-66" file="ch01_02.htm" sect="1.2.2. Invoking CGI Scripts"><primary>configuration</primary><secondary>CGI scripts, byweb servers</secondary></indexterm><indexterm id="INDEX-67" file="ch01_02.htm" sect="1.2.2. Invoking CGI Scripts"><primary>Unix operatingsystem</primary><secondary>executables, differentiating infilesystem</secondary></indexterm><indexterm id="INDEX-68" file="ch01_02.htm" sect="1.2.2. Invoking CGI Scripts"><primary>executablefiles, CGI scripts as</primary></indexterm><indexterm id="INDEX-69" file="ch01_02.htm" sect="1.2.2. Invoking CGI Scripts"><primary>operating systems</primary><secondary>CGIscripts, differences in handling of</secondary></indexterm><indexterm id="INDEX-70" file="ch01_02.htm" sect="1.2.2. Invoking CGI Scripts"><primary>commands</primary><secondary>executable files,creating on Unix</secondary></indexterm><indexterm id="INDEX-71" file="ch01_02.htm" sect="1.2.2. Invoking CGI Scripts"><primary>Unixoperating system</primary><secondary>executable files, commandsfor</secondary></indexterm><indexterm id="INDEX-72" file="ch01_03.htm" sect="1.3. Alternative Technologies"><primary>CGI (CommonGateway Interface)</primary><secondary>Perl language, advantages ofusing</secondary></indexterm><indexterm id="INDEX-73" file="ch01_03.htm" sect="1.3. Alternative Technologies"><primary>Perllanguage</primary><secondary>CGI</secondary><see>CGI programs,CGI</see></indexterm><indexterm id="INDEX-74" file="ch01_03.htm" sect="1.3.1. Why Perl?"><primary>strings</primary><secondary>perl treatmentof</secondary></indexterm><indexterm id="INDEX-75" file="ch01_03.htm" sect="1.3.1. Why Perl?"><primary>operators</primary><secondary>string manipulationin perl</secondary></indexterm><indexterm id="INDEX-76" file="ch01_03.htm" sect="1.3.1. Why Perl?"><primary>variables</primary><secondary>strict types, Perllacking requirement for</secondary></indexterm><indexterm id="INDEX-77" file="ch01_03.htm" sect="1.3.1. Why Perl?"><primary>data types</primary><secondary>strict variables,Perl language and</secondary></indexterm><indexterm id="INDEX-78" file="ch01_03.htm" sect="1.3.1. Why Perl?"><primary>numbers</primary><secondary sortas="perl">inperl</secondary>