An Anonymous Monk asked how to do something like this recently. Since there seems to be some demand for such a thing, and I was already working on it, here it is.

It prints:
A summary of errors and warnings, success and failure;
Projects with warnings, sorted most-warnings-first;
A list of successful projects;
A list of failed projects;
Every line that refers to "error" or "warning".

Many thanks to BrowserUK and many other monks for help with the GRT. Happy compiling...

use warnings;
use strict;

my $msg;
my $errors = 0;
my $warnings =0; 
my $failures = 0;
my $success = 0;
my @goodProjects; 
my @badProjects; 

open (LOG, "log.log")
    or die "Could not open log file: $!\n";

open (OUT, ">logSummary.txt") 
    or die "Could not open output file: $!\n";

my @msgs = <LOG>;

foreach $msg(@msgs) {
    if ($msg =~ ": error") {
        $errors++;
    }
    if ($msg =~ ": warning") {
        $warnings++;
    }
    if (($msg =~ "error") and ($msg =~ "warning") and !($msg =~ "0 err
+or")) {
        $failures++;
        push @badProjects, $msg;
    }
    if ($msg =~ "0 error") {
        $success++;
        push @goodProjects, $msg;
    }
}

#Guttman-Rosler Transform! 
my @sorted = map{
    substr $_, 5;
}sort {
    $b cmp $a
} map{
    m[,\s+(\d+)]
    ? sprintf '%05d%s', $1, $_
    : ()
} @msgs;
#End GRT

print OUT "\nBuild had approximately $errors errors.\n";
print OUT "Build had approximately $warnings warnings.\n";
print OUT "$failures projects failed to build.\n"; 
print OUT "$success projects built successfully.\n\n";
print OUT "Projects sorted according to number of warnings:\n";

foreach my $warning(@sorted) {
    print OUT $warning unless ($warning =~ ", 0 warning"); 
}

print OUT "\n\n";
print OUT "$success Successful projects:\n";
print OUT "@goodProjects";
print OUT "\n\n";
print OUT "$failures Failed projects:\n";
print OUT "@badProjects";
print OUT "\n\n";
print OUT "Detailed information about errors and warnings follows:\n\n
+";

foreach $msg(@msgs) {
    if (($msg =~ "error") or ($msg =~ "warning")) {
    print OUT $msg;
    }
}
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