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Backing Up Files Across Multiple Devices 
There you have them - sitting in a box. --From lots of CDs / DVDs, to far too many USB sticks to contemplate.

Rather than sitting there - waiting for us to toss them out - wouldn't it be nice if we could use them to backup our 'stuff?

Backup Splits

Much like in the days when we had lots of drive-tapes, the challenge is to split a `too-big` collection of files, across a `too-small` series of media. A problem almost as old as computing itself, fortunately all POSIX systems come with a program called `tar`!

sudo mkdir /d_backup 2> /dev/null
sudo chmod 777 /d_backup
cp $0 /d_backup
cd /d_backup
name=`date +d_drive_%Y_%j.tar`
echo Creating $name from $0
tar -cf ./$name /d_drive/
split -d -b 4480m ./$name

In the above, my task is to routinely back-up /d_drive into a folder named /d_backup. Once created, I want to split a julian-dated backup file into 4GB slices, from there to manually burn them out to a 2nd generation DVD drive. (*)

Splits Restored

To restore the files, all we need do is to (1) undo the `split,` by copying (2) all of the media-content to the hard drive, then (3) un-tar the concatenation:

cat * > d_drive.tar
tar xvf d_drive.tar

(*) Note that while the above `split` uses 4480 for the splits, that one should adjust the size to match the least-common size-denominator for any and all external media.

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Downgrading Java on Ubuntu 16.x 
Just a quick note to let everyone know that - after installing LTS 16.04 (so far a very pleasant & stable release - recommended!) that I discovered that the default JDK ("9 internal") does not work.

java -version
openjdk version "9-internal"

--The failures are so bad, that the kernel actually dumps core!

(Forgive the imp, yet note the bug -Halloween is around the corner!)

Sadly, removing the "9 internal" by conventional means results in only a partial removal... very nasty. What will work however, is to remove everything via a hand-grenade:

sudo apt remove --purge "^openjdk.*"

Followed by a dependency purge:
sudo apt-get autoremove

Then re-install a version that actually works:
sudo apt-get install openjdk-8-jre

Ultimately, once we have what we need installed, don't forget to associate that new JRE by right-clicking on a .jar file, so as to:

In addition to those old 'ol reliable versions of Oracle (I like to test under many JVM's), here is the OpenJDK that worked for me on LTS 16.04.1:
openjdk version "1.8.0_91"
OpenJDK Runtime Environment (build 1.8.0_91-8u91-b14-3ubuntu1~16.04.1-b14)
OpenJDK 64-Bit Server VM (build 25.91-b14, mixed mode)

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Installing MySQL Server & Workbench 
In a previous article we praised the innovative way Red Had allows us to rapidly install things like MySQL.

For the new learner however, note that at the time of this writing that only the MySQL Client (mysql-client) toolset will be installed.

Service, Please

If you are looking to do some R&D on your local host (we use a Virtual Box), then one will want to also install the MySQL Server tools (mysql-server), as well:

yum install mysql-server

Thereafter (*) we can start the locus via:

service mysqld start

As well as subsequently begin the MySQL console interface simply by typing
at the console interface.

MySQL Workbench

For those of us who absolutely love Microsoft SQL Server's SQL Management Studio (SSMS), note that MySQL has a must-have graphical tool set, as well. Formerly known as "MySQL Administrator", we now call it the "Workbench."

No matter what we call it however, the Community Edition of the GUI is the very next item most R&D folks will want to download.

Again at the time of this writing however, there is often an installation caveat. Before installation, try
yum install ... x86_64.rpm
if you run into problems whilst doing something like
yum install mysql-workbench-community-6.1.7-1.el6.x86_64.rpm
Once installed, merely enter
at the console to get things rolling.

Google Fodder

Installing the MySQL Server will resolve error message such as:
Error: Package: mysql-workbench-community-6.1.7-1.el6.x86_64 (/mysql-workbench-community-6.1.7-1.el6.x86_64) Requires:

[ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

-as well as:
mysqld: unrecognized service

or someday perhaps even:
mysqld: unrecognised service  ;-)

Ubuntu & Elsewhere

(*) Note that Ubuntu learns will want to use
sudo apd-get install mysql-server
sudo service mysqld start
rather than
yum ...
. Otherwise, everything else in this post will work the same.

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