Magic Banana suggested:> Just need to suppress that non-matching data ... which can be done with LibreOffice Calc in post processing by sorting and the deleting the rows with blank entries ...
> Are you referring to the lines where my command line does not detect any IPv4 address? If so, 'grep' can be used at the output:
$ tr -sc 0-9\\n ' ' < hostname_list | awk '{ k = 0; for (i = 0; k < 4 && ++i