MSG_DONTWAIT 設(shè)置為不可阻斷運作<br>
      MSG_NOSIGNAL 此動作不愿被SIGPIPE 信號中斷。<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 返回值 </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> 成功則返回實際傳送出去的字符數(shù)，失敗返回-1。錯誤原因存于errno<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 錯誤代碼 </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> EBADF 參數(shù)s 非合法的socket處理代碼。<br>
      EFAULT 參數(shù)中有一指針指向無法存取的內(nèi)存空間<br>
      ENOTSOCK 參數(shù)s為一文件描述詞，非socket。<br>
      EINTR 被信號所中斷。<br>
      EAGAIN 此操作會令進程阻斷，但參數(shù)s的socket為不可阻斷。<br>
      ENOBUFS 系統(tǒng)的緩沖內(nèi)存不足<br>
      ENOMEM 核心內(nèi)存不足<br>
      EINVAL 傳給系統(tǒng)調(diào)用的參數(shù)不正確。<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 范例 </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> 參考connect()<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top">　 
      <div align="right"><br>
        <font face='宋體' size='2'><a name=linuxc281></a></font> </div>
    </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> <br>
        </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> <br>
      sendmsg（經(jīng)socket傳送數(shù)據(jù)） </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 相關(guān)函數(shù) </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> send，sendto，recv，recvfrom，recvmsg，socket<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 表頭文件 </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> #include&lt;sys/types.h&gt;<br>
      #include&lt;sys/socket.h&gt;<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 定義函數(shù) </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> int sendmsg(int s,const strcut 
      msghdr *msg,unsigned int flags);<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 函數(shù)說明 </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> sendmsg()用來將數(shù)據(jù)由指定的socket傳給對方主機。參數(shù)s為已建立好連線的socket，如果利用UDP協(xié)議則不需經(jīng)過連線操作。參數(shù)msg 
      指向欲連線的數(shù)據(jù)結(jié)構(gòu)內(nèi)容，參數(shù)flags一般默認為0，詳細描述請參考send()。<br>
      結(jié)構(gòu)msghdr定義如下<br>
      struct msghdr<br>
      {<br>
      void *msg_name; /*Address to send to /receive from . */<br>
      socklen_t msg_namelen; /* Length of addres data */<br>
      strcut iovec * msg_iov; /* Vector of data to send/receive into */<br>
      size_t msg_iovlen; /* Number of elements in the vector */<br>
      void * msg_control; /* Ancillary dat */<br>
      size_t msg_controllen; /* Ancillary data buffer length */<br>
      int msg_flags; /* Flags on received message */<br>
      };<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 返回值 </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> 成功則返回實際傳送出去的字符數(shù)，失敗返回-1，錯誤原因存于errno<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 錯誤代碼 </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> EBADF 參數(shù)s 非合法的socket處理代碼。<br>
      EFAULT 參數(shù)中有一指針指向無法存取的內(nèi)存空間<br>
      ENOTSOCK 參數(shù)s為一文件描述詞，非socket。<br>
      EINTR 被信號所中斷。<br>
      EAGAIN 此操作會令進程阻斷，但參數(shù)s的socket為不可阻斷。<br>
      ENOBUFS 系統(tǒng)的緩沖內(nèi)存不足<br>
      ENOMEM 核心內(nèi)存不足<br>
      EINVAL 傳給系統(tǒng)調(diào)用的參數(shù)不正確。<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 范例 </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> 參考sendto()。<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top">　 
      <div align="right"><br>
        <font face='宋體' size='2'><a name=linuxc282></a></font> </div>
    </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> <br>
        </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> <br>
      sendto（經(jīng)socket傳送數(shù)據(jù)） </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 相關(guān)函數(shù) </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> send , sendmsg,recv , recvfrom 
      , socket<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 表頭文件 </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> #include &lt; sys/types.h &gt;<br>
      #include &lt; sys/socket.h &gt;<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 定義函數(shù) </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> int sendto ( int s , const void 
      * msg, int len, unsigned int flags, const <br>
      struct sockaddr * to , int tolen ) ;<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 函數(shù)說明 </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> sendto() 用來將數(shù)據(jù)由指定的socket傳給對方主機。參數(shù)s為已建好連線的socket,如果利用UDP協(xié)議則不需經(jīng)過連線操作。參數(shù)msg指向欲連線的數(shù)據(jù)內(nèi)容，參數(shù)flags 
      一般設(shè)0，詳細描述請參考send()。參數(shù)to用來指定欲傳送的網(wǎng)絡(luò)地址，結(jié)構(gòu)sockaddr請參考bind()。參數(shù)tolen為sockaddr的結(jié)果長度。<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 返回值 </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> 成功則返回實際傳送出去的字符數(shù)，失敗返回－1，錯誤原因存于errno 
      中。<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 錯誤代碼 </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> EBADF 參數(shù)s非法的socket處理代碼。<br>
      EFAULT 參數(shù)中有一指針指向無法存取的內(nèi)存空間。<br>
      WNOTSOCK canshu s為一文件描述詞，非socket。<br>
      EINTR 被信號所中斷。<br>
      EAGAIN 此動作會令進程阻斷，但參數(shù)s的soket為補課阻斷的。<br>
      ENOBUFS 系統(tǒng)的緩沖內(nèi)存不足。<br>
      EINVAL 傳給系統(tǒng)調(diào)用的參數(shù)不正確。<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 范例 </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> #include &lt; sys/types.h &gt;<br>
      #include &lt; sys/socket.h &gt;<br>
      # include &lt;netinet.in.h&gt;<br>
      #include &lt;arpa.inet.h&gt;<br>
      #define PORT 2345 /*使用的port*/<br>
      main(){<br>
      int sockfd,len;<br>
      struct sockaddr_in addr;<br>
      char buffer[256];<br>
      /*建立socket*/<br>
      if(sockfd=socket (AF_INET,SOCK_DGRAM,0))&lt;0){<br>
      perror (“socket”);<br>
      exit(1);<br>
      }<br>
      /*填寫sockaddr_in 結(jié)構(gòu)*/<br>
      bzero ( &addr, sizeof(addr) );<br>
      addr.sin_family=AF_INET;<br>
      addr.sin_port=htons(PORT);<br>
      addr.sin_addr=hton1(INADDR_ANY) ;<br>
      if (bind(sockfd, &addr, sizeof(addr))&lt;0){<br>
      perror(“connect”);<br>
      exit(1);<br>
      }<br>
      while(1){<br>
      bezro(buffer,sizeof(buffer));<br>
      len = recvfrom(socket,buffer,sizeof(buffer), 0 , &addr &addr_len);<br>
      /*顯示client端的網(wǎng)絡(luò)地址*/<br>
      printf(“receive from %s\n “ , inet_ntoa( addr.sin_addr));<br>
      /*將字串返回給client端*/<br>
      sendto(sockfd,buffer,len,0,&addr,addr_len);”<br>
      }<br>
      }<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 執(zhí)行 </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> 請參考recvfrom()<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top">　 
      <div align="right"><br>
        <font face='宋體' size='2'><a name=linuxc283></a></font> </div>
    </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> <br>
        </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> <br>
      setprotoent（打開網(wǎng)絡(luò)協(xié)議的數(shù)據(jù)文件） </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 相關(guān)函數(shù) </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> getprotobyname, getprotobynumber, 
      endprotoent<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 表頭文件 </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> #include &lt;netdb.h&gt;<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 定義函數(shù) </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> void setprotoent (int stayopen);<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 函數(shù)說明 </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> setprotoent()用來打開/etc/protocols， 
      如果參數(shù)stayopen值為1，則接下來的getprotobyname()或getprotobynumber()將不會自動關(guān)閉此文件。<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top">　 
      <div align="right"><br>
        <font face='宋體' size='2'><a name=linuxc284></a></font> </div>
    </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> <br>
        </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> <br>
      setservent（打開主機網(wǎng)絡(luò)服務(wù)的數(shù)據(jù)文件） </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 相關(guān)函數(shù) </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> getservent, getservbyname, getservbyport, 
      endservent<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 表頭文件 </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> #include &lt; netdb.h &gt;<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 定義函數(shù) </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> void setservent (int stayopen);<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 函數(shù)說明 </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> setservent()用來打開/etc/services，如果參數(shù)stayopen值為1，則接下來的getservbyname()或getservbyport()將補回自動關(guān)閉文件。<br>
      </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top">　 
      <div align="right"><br>
        <font face='宋體' size='2'><a name=linuxc285></a></font> </div>
    </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> <br>
        </font> </div>
    </td>
    <td valign="top"> <font face='宋體' size='2'> <br>
      setsockopt（設(shè)置socket狀態(tài)） </font> </td>
  </tr>
  <tr> 
    <td width="80" valign="top"> 
      <div align="right"><font face='宋體' size='2'> 相關(guān)函數(shù) </font> </div>
    </td>
    <td valign="