#Sample kafkacat command to move messages from one topic to another - one liner!
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#mycert2 topic is empty:
#####################################################################
mojave$ kafkacat -C -b localhost:9092 -t mycert2
% Reached end of topic mycert2 [0] at offset 0
% Reached end of topic mycert2 [1] at offset 0
% Reached end of topic mycert2 [2] at offset 0
^Cmojave$

#mycert topic has messages:
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mojave$ kafkacat -C -b localhost:9092 -t mycert
zero
one
two
well
how on earth
is this funny?
% Reached end of topic mycert [0] at offset 6
^Cmojave$

#redirect the consumer o/p of mycert until end of line (-e) to producer of empty topic:
#####################################################################

mojave$ kafkacat -C -b localhost:9092 -t mycert -e | kafkacat -P -b localhost:9092 -t mycert2
% Reached end of topic mycert [0] at offset 6: exiting
mojave$

#The empty topic got populated with the messages of the other topic:
#####################################################################
mojave$ kafkacat -C -b localhost:9092 -t mycert2
how on earth
one
two
zero
well
is this funny?
% Reached end of topic mycert2 [1] at offset 2
% Reached end of topic mycert2 [2] at offset 3
% Reached end of topic mycert2 [0] at offset 1
^Cmojave$