in reply to grep the data out of a text file.

Store the counts in a hash keyed by the category (i.e. A, B in your example). You also need a variable to remember the current category, its scope must be wider than the filehandle reading loop, because the number comes on a different line than the category, i.e. in a different iteration of the loop.

#!/usr/bin/perl
use warnings;
use strict;

my %violations_by_category;
my $category;
while (<DATA>) {
    if (/^([A-Z])_[0-9]+:/) {
        $category = $1;

    } elsif (/([0-9]+) violations?/) {
        $violations_by_category{$category} += $1;
    }
}

for my $category (keys %violations_by_category) {
    print $category, " ", $violations_by_category{$category}, "\n";
}

__DATA__
A_01: xxxxxxx
xxxxxxxxxx
xxx......... 1 violation

A_02: xxxxxxx
xxxxxxxxxx
xxx......... 4 violations
B_02: xxxxxxxx
xxxxxxxxxx
xxx......... 3 violations

[download]

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

[download]

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