Replace last octet in IPV6 address

successlin · 06-13-2019, 08:00 AM

Hi ,
I want to replace last octet in ip6 address say "fd01:cab:1:29::23b" with "fd01:cab:1:29::1".
I tried using cut, and other operators like "%%*" but not able to successfully do it.

berndbausch · 06-13-2019, 09:27 AM

The last octet or the last two octets? An octet is 8 bits.

Your example indicates you want two octets:

Code:

echo $IPADDRESS | sed ‘s/:[^:]*$/:1/‘

That replaces everything after the last colon. Testing is your responsibility.

If you only want to replace the last octet, it’s a bit more complicated, but should be doable with sed with little more effort.

syg00 · 06-13-2019, 05:19 PM

Personally I never use "*" unless absolutely unavoidable - it will match null expressions when you least expect it. Note also that sed supports the [:xdigit:] class.