匹配已知主機在正則表達式

Question

我怎麼能匹配警告以下，其中IP地址可以改變：

Warning: Permanently added '100.124.61.161' (RSA) to the list of known hosts. 

提前感謝！

Answer 1

您可以嘗試下面的代碼，更改字符串以僅限制特定文本。

if($string =~ m/Warning: Permanently added '(.*?)' \(RSA\) to the list of known hosts\./) 
{ 
    print "Match Successful, IP address: $1\n"; 
} 
else 
{ 
    print "String did not match\n"; 
} 

Answer 2

爲IPv4的（沒有端口）的一般的正則表達式。將
(?<!\d)(?:\d|[1-9]\d|1\d{2}|2[0-4]\d|25[0-5])(?:\.(?:\d|[1-9]\d|1\d{2}|2[0-4]\d|25[0-5])){3}(?!\d)

解釋

(?<! \d) 
(?: 
     \d      # 0 - 9 
    | [1-9] \d    # 10 - 99 
    | 1 \d{2}     # 100 - 199 
    | 2 [0-4] \d    # 200 - 249 
    | 25 [0-5]    # 250 - 255 
) 
(?: 
     \. 
     (?: 
      \d 
     | [1-9] \d 
     | 1 \d{2} 
     | 2 [0-4] \d 
     | 25 [0-5] 
    ) 
){3} 
(?! \d)