count

        #!/usr/bin/perl
        system("sort @ARGV | uniq -c | sort -n");

• That's all

• Note that if @ARGV is empty, it reads the standard input, as it should

• Funny story about this program

• For several months I had it wrong:

        #!/usr/bin/perl
        system("sort | uniq -c | sort @ARGV");

• This works fine when @ARGV is empty

• Fails when files are specified

• Because then the left sort hangs waiting for input

• The right sort has already sorted the file

• I didn't notice the missing -n either

• uniq -c's output can be sorted either way:

             9 63.164.145.33
            10 208.49.6.42
            86 6.0.3790.211
          1155 158.130.12.194

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Copyright © 2005 M. J. Dominus