add monitor host script

monitor-host/monitor-host.pl

@@ -0,0 +1,35 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+use Net::Ping::External qw(ping);
+
+my $target = shift;
+
+my $state = ping(host => $target);
+
+if ($state) {
+    print "monitoring $target (currently up)\n";
+}
+else {
+    print "monitoring $target (currently down)\n";
+}
+
+while (1) {
+    sleep 5;
+    my $alive = ping(host => $target);
+    if ($alive == 0 and $state == 1) {
+        system('notify-send', "$target just went down");
+    }
+    elsif ($alive == 1 and $state == 0) {
+        system('notify-send', "$target just came up");
+    }
+    if ($alive) {
+        print "$target is alive ($alive)\n";
+    }
+    else {
+        print "$target is down ($alive)\n";
+    }
+    $state = $alive;
+}