There is already Grep - print matched line and next N lines, and i know there is another one that handles the -B functionality as well as the -A, but i can't find it. Both of these (i think) were written before Tie::File was realeased, here is a version i just slapped together for the fun of it. :) Comments and suggestions are more than welcome. 
use strict;
use warnings;
use Tie::File;
use Getopt::Std;

our %opts;
getopt('AB',\%opts);
die "USAGE: $0 [-An] [-Bn] match file" unless @ARGV;
my ($match,$filename) = @ARGV;

my @file;
tie @file, 'Tie::File', $filename;

# i wish there was a way for grep to return indices ...
my @found;
for (0..$#file) {
   push @found, $_ if $file[$_] =~ /$match/;
}

for (@found) {
   my ($start,$end) = ($_,$_);

   $start -= $opts{A} if $opts{A};
   $end   += $opts{B} if $opts{B};
 
   $start = 0 if $start < 0;
   $end = $#file if $end > $#file;

   print $_,$/ for @file[$start..$end];
}

[download]
And yes, Perl is fun! :D

jeffa

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)

In reply to (jeffa) Re: linux grep feature by jeffa
in thread Emulating GNU grep -A and -B switches with perl (was: linux grep feature) by perlisfun

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