[AWK] Replace some key string if txt have two same keyword

awk '/1]/{x=NR+18}(NR<=x){print}' /nvram/8/rnddb.ini > /tmp/happy && \
awk '/2]/{x=NR+18}(NR<=x){print}' /nvram/8/rnddb.ini > /tmp/happy1 && \

awk 'BEGIN { FS = "[ \t]+" }; /^ipv4address/{$3="192.168.200.1"}1'  /tmp/happy1 > /tmp/happy2 && \

awk 'BEGIN { FS = "[ \t]+" } ; /^startaddress/{$3="192.168.200.2"}1'  /tmp/happy2 > /tmp/happy3 && \

awk 'BEGIN { FS = "[ \t]+" } ; /^endaddress/{$3="192.168.200.254"}1'  /tmp/happy3 > /tmp/happy4 && \

cat /tmp/happy /tmp/happy4 > /nvram/8/rnddb.ini


Reference :

• Different ways to print the next few lines after pattern match