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Oct 12, 2017

HOWTO: Notify user joined your Minecraft server (Nukkit or similar) using Notify My Android



So I setup a Minecraft server for my son and his friends, but it is hard to coordinate when they will all get online - so I decided to look into my options for notifications. In the end I went with Notify My Android (NMA). The NMA website provides a complete script for sending notifications via the Raspbian shell. The script can be found at the following location, I used the shell script, but there are other options - this guide focuses on the shell script:

http://www.notifymyandroid.com/dev.jsp

First thing we are going to do is log into our Raspbian system and let's make sure timezone is configured correctly:

sudo dpkg-reconfigure tzdata

Now let's download the notification script from NMA to your Raspberry Pi Minecraft server:

wget http://storage.locked.io/files/nma.sh

We need to do a couple of things with this file, first we need to make a change so that our NMA API key is in the file, using the following command:

sudo nano nma.sh

Edit APIKey= to use your API Key, you can find your own API Key from the NMA site.

Now we have to make the shell script executable:

chmod +x nma.sh

At this point we have a shell script that allows us to send notifications from Raspbian to NMA servers, and then to your Android. The next step is to create a short Perl file to monitor the Nukkit server.log (or any other log file for that matter). This script looks at the entire file, not just the tail, so if you run it against an existing server you are going to get a few notifications when first run. I called my file notify.pl:

sudo nano notify.pl

Enter the following into the notify.pl Perl script:

#Change /location/of/server.log in the following line to the real location of your server.log file

open(my $fd, "<", "/location/of/server.log") or die "Can't open log";
while(1) {
    if(eof $fd) {
        sleep 1;
        $fd->clearerr;
        next;
    }
    my $line = <$fd>;
#Parse the line into variables
my ($date, $time, $loglevel, $user, $operation) = split / /,$line;
    chomp($line);
    if($line =~ m/joined/) {
        system("./nma.sh \"Minecraft\" \"$user Joined\" \"At $time on $date $user $operation.\" 1");
    } elsif($line =~ m/left/) {
        system("./nma.sh \"Minecraft\" \"$user Left\" \"At $time on $date $user $operation.\" 1");
    }
}

Much like the NMA script we have to make our Perl script executable:

chmod +x notify.pl

That's it! Now you are going to have to run this at startup, much like you run your Minecraft server, so edit crontab:

crontab -e

Enter the following at the end of your file:

@reboot sleep 30 && sudo /usr/bin/perl /home/pi/notify.pl

The sleep is required to make sure the server has the log file available (didn't work for me without the sleep, I can only assume as the file is deleted on startup):

Reboot your server and you are good to go!
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