sed - match on IP octet and remove line

Question

I am in need of a solution, preferably sed, that can match on an IP octet that contains any number combination and remove the line. For example:

My file:

 192.168.100.12
 192.168.200.12
 10.10.20.10
 10.10.30.20

I need to remove the line that contains any IP found on the 10.10.20.x subnet and remove it. So, if the file contains 10.10.20.10 , 20.11, 20.12, etc... They all get removed. I also need an inline replacement.

What I have tried:

sed -i '/10\.10\.20\.\([0-9]\{1,3\}\)/d' file

and this:

sed -i '/10.\.10\.20\.*\([0-9]\{1,3\}\)*/d' file​

And neither one works. The command completes with no errors, but the lines are still in the file. I am also open to other solutions such as awk.

Answer 1

With GNU sed:

sed -i '/10\.10\.20\.[[:digit:]]\{,3\}/d' file

With BSD sed, you need sed -i ''.