Passing variables to awk

Note: the ENVIRON variables only work in bash for those that have been exported:

$ export ABCD=123; 
$ echo | awk '{print ENVIRON["ABCD"]}'
123

http://rosettacode.org/wiki/Environment_variables

The ENVIRON array contains the values of the current environment:
$ awk 'BEGIN{print "HOME:"ENVIRON["HOME"],"USER:"ENVIRON["USER"]}'
HOME:/home/suchrich USER:SuchRich
Environment variables can also be assigned to awk variables before execution, with (-v) options:
$ awk -v h=$HOME -v u=$USER 'BEGIN{prin