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ziggy (25)

ziggy
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Journal of ziggy (25)

Wednesday August 10, 2005
08:52 AM

nth

[ #26219 ]

Here's a little script I whipped up the other day. I'm grepping through a zillion files, all of which have the same structure but different data. Therefore, an operation like

$ grep '<span class="interesting">' *.html

produces about a dozen "interesting" lines of output per file. One thing I wanted to do was grab the 3rd such value from each file, and then compare them. Thus was born nth:

#!/usr/bin/perl -w

use strict;

my %values;
my @keys;

my $n = shift(@ARGV) -1;

while (<>) {
    my ($key) = m/^(.*?):/;

    push(@keys, $key) unless exists $values{$key};
    push(@{$values{$key}}, $_);
}

print map {$_->[$n] or "\n"} @values{@keys};

Extracting the interesting bits of data is now as simple as:

$ grep '<span class="interesting">' *.html | nth 3 | sed -e 'whatever'

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