while true:

     conn = server.accept()             #接受连接

     req   =  conn.read()                 #读取用去请求

     headers = parse_http(reqr)    #解析用户请求

     if is_static(headers[url]):         #如果是静态请求

         res_str = do_static(req_file)

     else if is_dynamic(headers[url]): #如果是动态请求

         res_str = do_dynamic(req)

     res_str = end_handler(res_str)  #对响应的字符串进行加工

     conn.write(res_str)                     #向用户输出相应的结果

     conn.close()                                #关闭连接

 函数名: exec...

 功  能: 装入并运行其它程序的函数

 用  法: int execl(char *pathname, char *arg0, arg1, ..., argn, NULL);

  int execle(char *pathname, char *arg0, arg1, ..., argn, NULL,

      char *envp[]);

  int execlp(char *pathname, char *arg0, arg1, .., NULL);

  int execple(char *pathname, char *arg0, arg1, ..., NULL,

       char *envp[]);

  int execv(char *pathname, char *argv[]);

  int execve(char *pathname, char *argv[], char *envp[]);

  int execvp(char *pathname, char *argv[]);

  int execvpe(char *pathname, char *argv[], char *envp[]);

 程序例: 

 /* execv example */

 #include <process.h>

 #include <stdio.h>

 #include <errno.h> 

 void main(int argc, char *argv[])

 {

    int i; 

    printf("Command line arguments:\n");

    for (i=; i<argc; i++)

       printf("[%2d] : %s\n", i, argv[i]); 

    printf("About to exec child with arg1 arg2 ...\n");

    execv("CHILD.EXE", argv); 

    perror("exec error"); 

    exit();

 } 

  Environment variables

    Environment variables are used to pass data about the request from

    the server to the script. They are accessed by the script in a system

    defined manner. In all cases, a missing environment variable is

    equivalent to a zero-length (NULL) value, and vice versa. The

    representation of the characters in the environment variables is

    system defined.

    Case is not significant in the names, in that there cannot be two

    different variable whose names differ in case only. Here they are

    shown using a canonical representation of capitals plus underscore

    ("_"). The actual representation of the names is system defined; for

    a particular system the representation may be defined differently to

    this.

    The variables are:

       AUTH_TYPE

       CONTENT_LENGTH

       CONTENT_TYPE

       GATEWAY_INTERFACE

       HTTP_*

       PATH_INFO

       PATH_TRANSLATED

       QUERY_STRING

       REMOTE_ADDR

       REMOTE_HOST

       REMOTE_IDENT

       REMOTE_USER

       REQUEST_METHOD

       SCRIPT_NAME

       SERVER_NAME

       SERVER_PORT

       SERVER_PROTOCOL

       SERVER_SOFTWARE

 #include    <stdio.h>

 #include    <sys/types.h>

 #include    <sys/stat.h>

 #include    <string.h>

 main(int ac, char *av[])

 {

     int     sock, fd;

     FILE    *fpin;

     char    request[BUFSIZ];

     if ( ac ==  ){

         fprintf(stderr,"usage: ws portnum\n");

         exit();

     }

     sock = make_server_socket( atoi(av[]) );

     if ( sock == - ) exit();

     /* main loop here */

     while(){

         /* take a call and buffer it */

         fd = accept( sock, NULL, NULL );

         fpin = fdopen(fd, "r" );

         /* read request */

         fgets(request,BUFSIZ,fpin);

         printf("got a call: request = %s", request);

         read_til_crnl(fpin);

         /* do what client asks */

         process_rq(request, fd);

         fclose(fpin);

     }

 }

 /* ------------------------------------------------------ *

    read_til_crnl(FILE *)

    skip over all request info until a CRNL is seen

    ------------------------------------------------------ */

 read_til_crnl(FILE *fp)

 {

     char    buf[BUFSIZ];

     while( fgets(buf,BUFSIZ,fp) != NULL && strcmp(buf,"\r\n") !=  )

         ;

 }

 /* ------------------------------------------------------ *

    process_rq( char *rq, int fd )

    do what the request asks for and write reply to fd

    handles request in a new process

    rq is HTTP command:  GET /foo/bar.html HTTP/1.0

    ------------------------------------------------------ */

 process_rq( char *rq, int fd )

 {

     char    cmd[BUFSIZ], arg[BUFSIZ];

     /* create a new process and return if not the child */

     if ( fork() !=  )

         return;

     strcpy(arg, "./");        /* precede args with ./ */

     if ( sscanf(rq, "%s%s", cmd, arg+) !=  )

         return;

     if ( strcmp(cmd,"GET") !=  )

         cannot_do(fd);

     else if ( not_exist( arg ) )

         do_404(arg, fd );

     else if ( isadir( arg ) )

         do_ls( arg, fd );

     else if ( ends_in_cgi( arg ) )

         do_exec( arg, fd );

     else

         do_cat( arg, fd );

 }

 do_exec( char *prog, int fd )

 {

     FILE    *fp ;

     fp = fdopen(fd,"w");

     header(fp, NULL);

     fflush(fp);

     dup2(fd, );

     dup2(fd, );

     close(fd);

     execl(prog,prog,NULL);

     perror(prog);

 }