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$ perl -ple 's/\s+/ /g' today | sort > today.s $ perl -ple 's/\s+/ /g' yesterday | sort > yesterday.s $ comm -3 today.s yesterday.s
$ comm -3 <(perl -ple 's/\s+/ /g' today | sort) <(perl -ple 's/\s+/ /g +' yesterday | sort)