I am looking to extract a dynamic port number from a text file and print it in to a new text file.

The surrounding text stays the same.

Currently I am using:

sed -n '89p' originalfile.txt | cut -c 16- > newfile.txt

Line 89 of originalfile.txt is:

Forwarded port 12345

and then newfile.txt only contains that 5 digit number.

This has been working, except some times the line number changes from 89 to something else, and I was looking for a more permanent solution?

Another piece of text in originalfile.txt is this, which may be better to use:

--> The port is 12345 and it will expire on 2024-08-28T23:50:18. <--

Thank you