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ittechlabFlag for Canada

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awk - sample

$(/sbin/ifconfig -a | /usr/bin/awk 'BEGIN {ips=""} /inet/ && $2 !~ /127.0.0/ {ips=ips", "$2} END {print substr(ips,3)}')

can some one explain me how BEGIN and END works with awk?

what is IPS?

I also want to know how above line executes?
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ozo
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man awk
...
       A pattern-action statement has the form

              pattern { action }
...
       The  special  patterns  BEGIN  and END may be used to capture control before the first input line is read and after the last.  BEGIN and END do not combine
       with other patterns.
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Bill Prew

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simon3270
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Hi ittechlab,

I agree with what the experts above have said, but would add that in this example, the:
  BEGIN {ips=""}
section seems to be unnecessary because in awk, variables can be referenced and appended (e.g. {ips=ips", "$2}) even if they have not been explicitly initialised to "" beforehand.

So, this should do the same thing (and based on my tests, it does):
    $(/sbin/ifconfig -a | /usr/bin/awk '/inet/ && $2 !~ /127.0.0/ {ips=ips", "$2} END {print substr(ips,3)}')