#!/usr/bin/env perl

use strict;

if ($#ARGV != 0) { 
	print "Usage: rmk [ssh_know_hosts]:line\n";
	exit 1 ;
} 

$ARGV[0] =~ /([^:]*):(\d+)$/;

my $kh = $1 ? $1 : $ENV{HOME}."/.ssh/known_hosts";
my $ln = $2;

open(my $khh, "+<", $kh);

my @khc = ();
my $i = 1;

while (<$khh>) {
	push (@khc, $_) if ($i != $ln);
	$i++;
}

seek($khh, 0, "SEEK_SET");

for (@khc) {
	print $khh $_;
}

truncate($khh, tell($khh));