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Python多行正则表达式忽略字符串中的n行

multiline regex python

Jegor · 技术社区 · 7 年前

我写正确的正则表达式有问题。也许有人能帮我?

我有两个网络设备的输出:

VRF NAME1 (VRF Id = 2); default RD 9200:1; default VPNID <not set>
Old CLI format, supports IPv4 only
Flags: 0xC
Interfaces:
Gi1/1/1                 Gi1/1/4

VRF NAME2 (VRF Id = 2); default RD 101:2; default VPNID <not set>
Interfaces:
Gi0/0/3                  Gi0/0/4                  Gi0/1/4

我需要从两者中提取接口名称。

我有正则表达式:

 rx = re.compile("""
              VRF\s(.+?)\s\(.*RD\s(.*);.*[\n\r]
              ^.*$[\n\r]
              ^.*$[\n\r]
              ^.*$[\n\r]
              (^.*)
              """,re.MULTILINE|re.VERBOSE)

但它只适用于第一个文本,它跳过了4行,5行正是我需要的。然而,有许多路由器返回输出,如2。

3 回复 | 直到 7 年前

Marc Lambrichs user8588010 7 年前

编辑:在为我们提供更多输入后,答案被更正。

有很多方法可以解决这个问题。看看 regex101 . 正则表达式

(?s)VRF\s([^\s]+)\s.*?(?:RD\s([\d.]+:\d|<not\sset>));.*?Interfaces:(?:\r*\n)\s*(.*?)(?:\r*\n)

Interfaces .

说明:

(?s)                           # single line mode: make "." read anything,
                               # including line breaks
VRF                            # every records start with VRF
\s                             # read " "
([^\s]+)                       # group 1: capture NAME VRF
\s                             # read " "
.*?                            # lazy read anything
(?:                            # start non-capture group
 RD\s                          # read "RD "
(                              # group 2
  [\d.]+:\d                    # number or ip, followed by ":" and a digit
  |                            # OR
  <not\sset>                   # value "<not set>"
)                              # group 2 end
)                              # non-caputure group end
;                              # read ";"
.*?                            # lazy read anything
Interfaces:                    # read "Interfaces:"
(?:\r*\n)                      # read newline
\s*                            # read spaces
(.*?)                          # group 3: read line after "Interfaces:"
(?:\r*\n)                      # read newline

$ cat test.py
import os
import re

pattern = r"(?s)VRF\s([^\s]+)\s.*?(?:RD\s([\d.]+:\d|<not\sset>));.*?Interfaces:(?:\r*\n)\s*(.*?)(?:\r*\n)"

text = '''\
VRF BLA1 (VRF Id = 2); default RD 9200:1; default VPNID <not set>
Old CLI format, supports IPv4 only
Flags: 0xC
Interfaces:
  Gi1/1/1.451              Gi1/1/4.2019
Address family ipv4 unicast (Table ID = 0x2):
  VRF label allocation mode: per-prefix
Address family ipv6 unicast not active
Address family ipv4 multicast not active

VRF BLA2 (VRF Id = 1); default RD <not set>; default VPNID <not set>
New CLI format, supports multiple address-families
Flags: 0x1808
Interfaces:
  Gi0
Address family ipv4 unicast (Table ID = 0x1):
  Flags: 0x0
Address family ipv6 unicast (Table ID = 0x1E000001):
  Flags: 0x0
Address family ipv4 multicast not active\
'''

for rec in text.split( os.linesep + os.linesep):
    m = re.match(pattern, rec)
    if m:
        print("%s\tRD: %s\tInterfaces: %s" % (m.group(1), m.group(2), m.group(3)))

这导致:

$ python test.py
BLA1    RD: 9200:1  Interfaces: Gi1/1/1.451              Gi1/1/4.2019
BLA2    RD: <not set>   Interfaces: Gi0

Community CDub 5 年前

正面回顾

(?<=…)

https://regex101.com/

正则表达式 (?<=Interfaces:\n).+ 匹配每行“接口:”

我在regex101上测试了它。com,它与您的两个示例都完美地结合在一起。

koalo 7 年前

有多个选项,但最接近初始尝试的选项使用可选的未捕获行:

rx = re.compile("""
VRF\s(.+?)\s\(.*RD\s(.*);.*[\n\r]
(?:^.*$[\n\r])?
(?:^.*$[\n\r])?
Interfaces:[\n\r]
(.*)""",re.MULTILINE|re.VERBOSE)

(?:^.*$[\n\r])? 在应用程序中工作。