Extracting from a file and pasting details to another file - linux

Question

The problem is regarding extracting the details of the Oracle Virtual box(2nd paragraph) from the "nmap non-gui version". I understand the usage of "grep" and "loops" and have already tried everything but what if there are other systems connected on the same network. I just want the program to find the word "(Oracle VirtualBox virtual NIC)" and extract everything above it until it finds a blank-line.
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root#PopeyeTheSailorMan:~# nmap 192.168.43.0/24 > Log.txt
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Starting Nmap 7.60 ( https://nmap.org ) at 2017-11-15 04:08 UTC
Nmap scan report for 192.168.43.1
Host is up (0.0025s latency).
Not shown: 999 closed ports
PORT STATE SERVICE
53/tcp open domain
MAC Address: 9A:10:94:51:42:ED (Unknown)
***Nmap scan report for 192.168.43.136
Host is up (0.00071s latency).
Not shown: 994 closed ports
PORT STATE SERVICE
22/tcp open ssh
80/tcp open http
111/tcp open rpcbind
139/tcp open netbios-ssn
443/tcp open https
1024/tcp open kdm
MAC Address: 08:00:27:D3:73:2E (Oracle VirtualBox virtual NIC)***
Nmap scan report for kali (192.168.43.79)
Host is up (0.0000070s latency).
All 1000 scanned ports on kali (192.168.43.79) are closed
Nmap done: 256 IP addresses (3 hosts up) scanned in 16.00 seconds

Answer 1

If I understand your question, this does what you want:
awk '/Oracle VirtualBox virtual NIC/' RS= Log.txt
With your sample input:
$ awk '/Oracle VirtualBox virtual NIC/' RS= Log.txt
***Nmap scan report for 192.168.43.136
Host is up (0.00071s latency).
Not shown: 994 closed ports
PORT STATE SERVICE
22/tcp open ssh
80/tcp open http
111/tcp open rpcbind
139/tcp open netbios-ssn
443/tcp open https
1024/tcp open kdm
MAC Address: 08:00:27:D3:73:2E (Oracle VirtualBox virtual NIC)***
How it works
RS=
This tells awk to read input a paragraph at a time.
/Oracle VirtualBox virtual NIC/
This tells awk to print any paragraph that contains the string Oracle VirtualBox virtual NIC.

Answer 2

grep -n ^$ Log.txt | sed s/://
will give the blank line numbers (suitable for an array)
grep -n 'Oracle VirtualBox virtual NIC' Log.txt | cut -f1 -d\:
will give the line numbers of the target
Use arrays, loops and sed to grok the block you want
sed -n '8,19p' Log.txt