need example for awk command and awk within awk command in in shell script

I need a simple working example that makes me under开发者_C百科stand

1, awk command in shell script. 2, awk withing awk command in shell script.

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I'm not really sure what the point is, but here's awk calling awk from within a shell script...

#!/bin/sh

cmd='BEGIN {print \"foo\"}'
echo foo |
awk "{ system( \"awk '$cmd'\" )}"