Perl getprotoent 函数

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  描述

  getprotoent 此函数返回有效协议列表中的下一个条目：（$name，$aliases，$protocol_number）。
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  句法

  以下是此函数的简单语法-

  
  getprotoent
  

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  返回值

  此函数对错误返回undef，否则返回标量上下文中的协议编号，并在列表上下文中返回错误协议记录上的空列表（名称，别名，协议编号）。
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  示例

  以下是显示其基本用法的示例代码-

   
  while(($name, $aliases, $protocol_number) = getprotoent()) {
     print "Name = $name\n";
     print "Aliases = $aliases\n";
     print "Protocol Number = $protocol_number\n";
  }
  

  尝试一下

  执行结果：

  
  Name = ip
  Aliases = IP
  Protocol Number = 0
  Name = hopopt
  Aliases = HOPOPT
  Protocol Number = 0
  Name = icmp
  Aliases = ICMP
  Protocol Number = 1
  Name = igmp
  Aliases = IGMP
  Protocol Number = 2
  Name = ggp
  Aliases = GGP
  Protocol Number = 3
  Name = ipencap
  Aliases = IP-ENCAP
  Protocol Number = 4
  Name = st
  Aliases = ST
  Protocol Number = 5
  Name = tcp
  Aliases = TCP
  Protocol Number = 6
  Name = egp
  Aliases = EGP
  Protocol Number = 8
  Name = igp
  Aliases = IGP
  Protocol Number = 9
  Name = pup
  Aliases = PUP
  Protocol Number = 12
  Name = udp
  Aliases = UDP
  Protocol Number = 17
  Name = hmp
  Aliases = HMP
  Protocol Number = 20
  Name = xns-idp
  Aliases = XNS-IDP
  Protocol Number = 22
  Name = rdp
  Aliases = RDP
  Protocol Number = 27
  Name = iso-tp4
  Aliases = ISO-TP4
  Protocol Number = 29
  Name = dccp
  Aliases = DCCP
  Protocol Number = 33
  Name = xtp
  Aliases = XTP
  Protocol Number = 36
  Name = ddp
  Aliases = DDP
  Protocol Number = 37
  Name = idpr-cmtp
  Aliases = IDPR-CMTP
  Protocol Number = 38
  Name = ipv6
  Aliases = IPv6
  Protocol Number = 41
  Name = ipv6-route
  Aliases = IPv6-Route
  Protocol Number = 43
  Name = ipv6-frag
  Aliases = IPv6-Frag
  Protocol Number = 44
  Name = idrp
  Aliases = IDRP
  Protocol Number = 45
  Name = rsvp
  Aliases = RSVP
  Protocol Number = 46
  Name = gre
  Aliases = GRE
  Protocol Number = 47
  Name = esp
  Aliases = IPSEC-ESP
  Protocol Number = 50
  Name = ah
  Aliases = IPSEC-AH
  Protocol Number = 51
  Name = skip
  Aliases = SKIP
  Protocol Number = 57
  Name = ipv6-icmp
  Aliases = IPv6-ICMP
  Protocol Number = 58
  Name = ipv6-nonxt
  Aliases = IPv6-NoNxt
  Protocol Number = 59
  Name = ipv6-opts
  Aliases = IPv6-Opts
  Protocol Number = 60
  Name = rspf
  Aliases = RSPF CPHB
  Protocol Number = 73
  Name = vmtp
  Aliases = VMTP
  Protocol Number = 81
  Name = eigrp
  Aliases = EIGRP
  Protocol Number = 88
  Name = ospf
  Aliases = OSPFIGP
  Protocol Number = 89
  Name = ax.25
  Aliases = AX.25
  Protocol Number = 93
  Name = ipip
  Aliases = IPIP
  Protocol Number = 94
  Name = etherip
  Aliases = ETHERIP
  Protocol Number = 97
  Name = encap
  Aliases = ENCAP
  Protocol Number = 98
  Name = pim
  Aliases = PIM
  Protocol Number = 103
  Name = ipcomp
  Aliases = IPCOMP
  Protocol Number = 108
  Name = vrrp
  Aliases = VRRP
  Protocol Number = 112
  Name = l2tp
  Aliases = L2TP
  Protocol Number = 115
  Name = isis
  Aliases = ISIS
  Protocol Number = 124
  Name = sctp
  Aliases = SCTP
  Protocol Number = 132
  Name = fc
  Aliases = FC
  Protocol Number = 133
  Name = mobility-header
  Aliases = Mobility-Header
  Protocol Number = 135
  Name = udplite
  Aliases = UDPLite
  Protocol Number = 136
  Name = mpls-in-ip
  Aliases = MPLS-in-IP
  Protocol Number = 137
  Name = manet
  Aliases = 
  Protocol Number = 138
  Name = hip
  Aliases = HIP
  Protocol Number = 139
  Name = shim6
  Aliases = Shim6
  Protocol Number = 140
  Name = wesp
  Aliases = WESP
  Protocol Number = 141
  Name = rohc
  Aliases = ROHC
  Protocol Number = 142