Maybe on windows but not a UNIX. 
bruce:0:~/tmp $ export fred=1
bruce:0:~/tmp $ env | grep fred
fred=1
bruce:0:~/tmp $ perl -e 'print $ENV{fred},"\n"'
1
bruce:0:~/tmp $ perl -e 'print $ENV{FRED},"\n"'

bruce:0:~/tmp $

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In reply to Re^2: Case insensitive keys in global %ENV by bruceb3
in thread Case insensitive keys in global %ENV by bdimych

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