输出CGI环境变量

用C写的，输出CGI的环境变量.

路径:/var/www/cgi-bin/
编译:gcc -o cgi_env cgi_env.c -std=c99
在浏览器中输入http://localhost/cgi-bin/cgi_env 或者 http://ip/cgi-bin/cgi_env

//cgi_env.c
#include        <stdlib.h>
#include        <stdio.h>

int main ( int argc, char *argv[] )
{
    char *env_var[ 24 ] = {
    "COMSPEC", "DOCUMENT_ROOT", "GATEWAY_INTERFACE",
    "HTTP_ACCEPT", "HTTP_ACCEPT_ENCODING",
    "HTTP_ACCEPT_LANGUAGE", "HTTP_CONNECTION",
    "HTTP_HOST", "HTTP_USER_AGENT", "PATH",
    "QUERY_STRING", "REMOTE_ADDR", "REMOTE_PORT",
    "REQUEST_METHOD", "REQUEST_URI", "SCRIPT_FILENAME",
    "SCRIPT_NAME", "SERVER_ADDR", "SERVER_ADMIN",
    "SERVER_NAME","SERVER_PORT","SERVER_PROTOCOL",
    "SERVER_SIGNATURE","SERVER_SOFTWARE" };

    printf ( "%s\n","Content-Type: text/html\n" );
    printf ( "%s\n","1.0\"?>" );
    printf ( "%s\n","-//W3C//DTD XHTML 1.1//EN\" " );
    printf ( "%s\n","\"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd\">" );
    printf ( "%s\n","http://www.w3.org/1999/xhtml\">" );
    printf ( "%s\n","CGI环境变量" );
    printf ( "%s\n","0\" cellspacing = \"2\">");

    for ( int i=0;i<24;i++ ) {
        printf ( "%s%s%s\n","");
    }
    printf ( "%s\n"," ",env_var[i],"" );
        char *value = getenv( env_var[i]);

        if ( value ) {
            printf ( "%s",value );
        }
        else {
            printf ( "%s","CGI环境变量不存在." );
        }
        printf ( "%s\n"," 
" );

    for ( int i=0;i<24;i++ ) {
        printf ( "%s%s%s\n","
    }
    printf ( "%s\n","
        char *value = getenv( env_var[i]);

        if ( value ) {
            printf ( "%s",value );
        }
        else {
            printf ( "%s","CGI环境变量不存在." );
        }
        printf ( "%s\n","
    printf ( "%s\n","C语言编写" );
    return EXIT_SUCCESS;
}