Remove IPv6 addresses from a list using sed

Question

Using avahi I have populated a list of ip-addresses on my network range. The information populated is then refined using sed to give the following output

Initial data = address = [xxx.xxx.xxx.xxx]
Refined data = xxx.xxx.xxx.xxx

The command to do so is as follows:

avahi-browse -alrt | grep -w address | sort -u | sed -e 's/address = //' | sed -e 's/\[//' | sed -e 's/\]//'

This works correctly most of the time however on the odd occasion addresses such as xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx are displayed in the list and I would like to omit them.

I know I could possibly use a regex expression or something to ensure the data always matches a valid ip i.e xxx.xxx.xxx.xxx but I am unsure as to how to go about this. Any help is much appreciated.

The command is run on linux using a bash script and I wish it to return only the valid ip addresses in the xxx.xxx.xxx.xxx format.

Answer 1

Replace your 3 sed commands with this one:

sed 's/address = \[\|\]//g' 

OR:

sed -r 's/address = \[|\]//g' 

EDIT: To remove invalid IPs also use this sed:

sed -r -e 's/address = \[|\]//g' -e 's/= +([^:]+\:){5,}.*$/=/' file

Answer 2

Try replacing your three sed commands with following one

sed -nr 's/.*address = \[(([0-9]{1,3}\.){3}[0-9]{1,3})\].*/\1/p'

Answer 3

avahi-browse -alrt | sed -n "/address/ s/address = \[\(\([012]\{0,1\}[0-9]\{0,1\}[0-9]\.\)\{3\}[12]\{0,1\}[0-9]\{0,1\}[0-9]\)\].*/\1/p" | sort -u

sort could be done before but is certainly faster after the sed and grep is not needed because sed could also filter the lines. (not tested because not shell here)