search and Replace substring in mac address in a text file

Question

Below is extract from the file to be changed: May use awk or sed...any utility is good for pattern matching

mgad 1
m-id         50
rf-chan-id   1
base-station-id 00:a0:bc:0c:1b:c1
....
....
mgad 2
....
base-station-id 00:a0:bc:0c:1b:c2
....
....
mgad 3
....
base-station-id 00:a0:bc:0c:1b:c3
....
....
mgad 4
base-station-id 00:a0:bc:0c:1b:c4

I have to edit mac address in the 5th position from 00:a0:bc:0c:XX:c3 to 00:a0:bc:0c:18:c3 for multiple lines in the file. PN: 5th position can be variable,needs to be changed to "18"

I tried this:

sed -En ' s/^\( base-station-id.* [0-9A-Fa-f]{2}\:[0-9A-Fa-f]\:[0-9A-Fa-f]\:[0-9A-Fa-f]\:\)[0-9A-Fa-f]+\(\:.*\)$/\118\2/p; '

Please help with correct regex pattern matching and replace with desired change in substring in mac address

Answer 1

Capture the leading portion; allow any two characters in the 5th position of the MAC, then capture the trailing portion, and replace it with the 1st captured group, the text 18, and the 2nd captured group:

sed 's/\(base-station-id ..:..:..:..:\)..\(:..\)/\118\2/' < input > output