sort -u input.txt |\
    perl -pe '$r = substr(rand(), 2); $_ = "$r\t$_"' |\
    sort -n | cut -f 2- > output.txt

[download]
sort is optimized to work well with really large files. You may want to use the -S and -T parameters on sort.

In reply to Re: Strategy for randomizing large files via sysseek by Anonymous Monk
in thread Strategy for randomizing large files via sysseek by Anonymous Monk

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