Don't mean to be rude, but this can be done a lot simpler: 
perl -ne '$s{lc $_}++ or print'

[download]
(It's actually a standard example to which I added lc, and unlike your version it prints out the line right at its first occurrance, rather than first slurping in the whole file)

In reply to Re: state preserving uniq by xmath
in thread state preserving uniq by Chady

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