regex find text block when it start with but does not contain

While processing the logs we receive from our routers I'v encountered a problem.
In fact these logs are just scripted console outputs we receive from our network provider.
We have heen able to process some blocks but now I'm encoutering another problem with regex.
This is a sample of the log

   PADB067# show vrrp
    % No entries found.
    PADB067# show run vpn 0  | i weight
    PADB067# show run vpn 0 
    vpn 0
     name Transport
     dns 4.2.2.2 secondary
     dns 8.8.8.8 primary
     host vbond-list ip x.x.x.x y.y.y.y z.z.z.z
     interface ge0/0
      description           "ORCH=NETWORK - To INTERNET"
.....
      tunnel-interface
       encapsulation ipsec preference 0
      !
      icmp-redirect-disable
      no shutdown
      shaping-rate          20480
      qos-map               COS-OUT-SHAPED
      bandwidth-upstream    20480
      bandwidth-downstream  20480
     !
     interface ge0/3
      description "ORCH=NETWORK - CUSTOMER LAN - Service VPN physical interface"
      mtu         1504
      no shutdown
    !
    PADB067# show run vpn 1
    vpn 1

Some routers don't have all blocks, in this case I want to find the block between "show run vpn 0" and the next routername, this is the regex.

(?<=show run vpn 0)(?s)(.*?)(?=PADB067)

But I don't want it to start at "show run vpn 0 | i weight", that is another data block (that in this case is not present for that router).
So bottom line I'm searching for the correct regex that would 'think'

Find the text block after "show run vpn 0" when the line does not include "weight", until "PADB067"

Kr, Harry

With [tag:awk]:

awk '/PADB067# show run vpn 0/{p=1;next} /PADB067# show run vpn /{exit}p' file

You can use this regex:

(?<=show run vpn 0 [\r\n])[\s\S]*?(?=\s*PADB067\b)

Explanation of regex:

• (?<=show run vpn 0 [\r\n]) -- positive lookbehind for expected text and newline
• [\s\S]*? -- non-greedy scan ([\s\S]*? is any chars including newlines; use .*? instead with s flag)
• (?=\s*PADB067\b) -- positive lookbehind for whitespace and PADB067 with word boundary

Learn more about regex: https://twiki.org/cgi-bin/view/Codev/TWikiPresentation2018x10x14Regex

You can omit the online (?s) and then match 1 or more lines that do not start with PAD and a digit if you want a more general approach instead of hardcoded PADB067.

Note that there is a space after vpn 0 in the example data

(?<=show run vpn 0 )(?:\n(?![^\S\n]*PADB\d+\b).*)+

Explanation

• (?<=show run vpn 0 ) Positive lookbehind, assert that the text is directly to the left of the current position
• (?: Non capture group to repeat as a whole part
  • \n Match a newline (Or use \r?\n)
  • (?![^\S\n]*PADB\d+\b) Negative lookahead, assert that the string does not start with optional spaces followed by PADB and 1 or more digits
  • .* Match the whole line
• )+ Close the non capture group and repeat it 1 or more times

Regex demo