a comment on

"Also be nice if I could pipe to it also so tail -f <LOG> | log_grepper.pl.. "

I use the following sample code structure to read files in a 'tail' ing fashion:

#!/usr/bin/perl -w

my $targetF = "/var/log/local2";

for(;;) {
    open ML, "<$targetF" || die $!;
    #seek(ML, 0, 2); # to EOF - Not, process from beginning
    
    for (;;){
        while (<ML>){
            another_line();
        }
        sleep 2;
        seek(ML,  0, 1); # reset end-of-file error
    }
    # dropping here with the 'last' should cause
    # the file being monitored to be closed and reopened
    close (ML);
}

sub another_line {
    # $_ has the line
    # Check for target phrases
    return;
}
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(I can't remember which book I found this in, but I find it very useful.)

But any cyclically incremental reading of the file adds the need for accumulation of multi-line events, handling partial (incomplete) lines, and all the other 'streaming' techniques.