#!/usr/bin/perl -w
# adds a string after a line matching pattern from each file.
# usage: aline PATTERN STRING FILES

use Tie::File;
use strict;

my $file;
my $k;
my @lines;
my $pat = shift || die "no pattern";
my $str = shift || die "no string to add";

foreach $file (@ARGV) {
    tie(@lines, 'Tie::File', "$file") or die "$file: can't update";
    $k = 0;
    for (@lines) {
        if (/$pat/) {
            splice (@lines, $k+1, 0, $str);
            last;
        }
        $k++;
    }
    untie @lines;
}

exit(0);