Adding an item to the Ubuntu Unity Launcher

I would begin this post by saying something pithy about the latest Brexit crisis gripping the nation. However, watching any news or current affairs program at the moment leaves me feeling rather like this :

Fortunately, I had a new version of SQLDeveloper to install on my Ubuntu 16.04 laptop to take my mind off things.
After installing the software, I forgot – as I almost always do – how to add a new item to the Unity Launcher, so I thought I’d write down the steps this time.

Unity is similar to Gnome, KDE and – as it turns out – XFCE in that it seems to follow the freedesktop.org Desktop Entry Specification.
So, all I need to do is :

  • create a .desktop file in a suitable location to tell Unity how to run SQLDeveloper
  • add it to the Unity Launcher
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Installing and Configuring Oracle 18cXE on CentOS

After seven years, the much anticipated Oracle 18c Express Edition (XE) has finally seen the light of day.
Reaction to the new version can be summed up as…

It’s the Dog’s Wotsits !

Gerald Venzl, the person we have to thank for this new and vastly improved version of XE, has already published an installation guide.

At this point you may well ask yourself that what – apart from gratuitous puppy pics and cheesy-snack-based puns – is the difference between that post and this.

Well, if you’re a long-time user of 11gXE and you’re looking to upgrade then you will find 18cXE a rather different proposition.
The introduction of Multitenant databases aside, 18cXE differs greatly from it’s predecessor in terms of it’s functional scope.
Wheras 11gXE was – broadly speaking – functionally equivalent to Oracle Standard Edition, the approach for 18cXE has been to shoe-horn in as many Enterprise Edition features as possible.
No doubt, this will leave you anxious to play with the new version. However, there are some “home comforts” that were present in the old version that you’ll need to configure yourself this time around.
What I’m going to go through is :

  • Installing 18cXE on a Red Hat compatible distro (CentOS7)
  • Connecting to the database and exploring the containers
  • Checking the TNS Listener
  • Manual and Automatic Startup and Shutdown of the database and listener
  • Setting and persisting the Oracle environment variables
  • Accessing Enterprise Manager Express
  • Installing the HR demo application in a Pluggable Database (PDB)
  • Configuring the firewall to allow remote access to Oracle

The steps documented here have been performed on a vanilla installation of CentOS7. As such, they should work pretty much unaltered for other Red Hat based distros based on or similar to Red Hat Enterprise Linux (RHEL) version 7.

Before all of that though… Continue reading

VirtualBox – configuring a Host-Only Network

I’m currently indulging in the pastime that’s sweeping the country – trying not to think about Brexit.
It’s a craze that’s even spread as far our political elite. In their case, it manifests itself in slightly different ways.
On the one hand, there are those who are refusing to accept any solution offered to maintain a “soft” border on the island of Ireland. As far as I can tell, they haven’t managed to offer any practical solution that they would accept as that would involve thinking about Brexit.
On the other hand there are those who are pushing for a new referendum because, apparently, some politicians lied when campaigning. Maybe someone was “Putin” ’em up to it ?

For my part, as I don’t quite have the space for a bunker at the bottom of my garden, I’ve decided to hide out in to a world of make-believe…well Virtual Machines at any rate.

I want to setup a CentOS Virtual Machine (VM) that I can then use as to clone environments to host various software stacks that I may want to play with.
I’d like to be able to connect to these VMs directly from my host OS, just like a real-world server. However, I’d also like to be able to connect the VM to the outside world occasionally so I can run package updates via yum.
The specific steps I’m going to go through are :

  • Install CentOS7 into a Virtualbox VM
  • Setup Host Only Network in VirtualBox
  • Create a Network Interface on the Guest to use the Host Only Network
  • Assign a static IP address to the Guest

The software I’m using for this is :

Before we get cracking, it’s probably a good idea to have a quick look at… Continue reading

New Dog, Old Tricks – how to save yourself some typing with sed

We have a new addition to our household –

Teddy


Cute and fluffy he may be, but he’s got to earn his keep. He can start making himself useful by helping me with this post.

It begins one Friday afternoon when an urgent request lands on my desk with a large splat.

The requirement is that some csv files be uploaded into the Oracle 11g Datbasae serving the UAT environment to facilitate some testing.
There are around 20 files, each with a slightly different set of attributes.
The files are currently sitting on the on the Red Hat Linux Server hosting the database.
I have sufficient OS permissions on the server to move them to a directory that has a corresponding database object in the UAT instance.
Nevertheless, the thought of having to knock out 20-odd external tables to read these files might leave me feeling a bit like this…


Fortunately, a certain Lee E. McMahon had the foresight to predict the potential risk to my weekend and wrote the Stream Editor (sed) program

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Cocktails and Traffic Cones – party time with DVDs and Blu-Rays in Ubuntu

This title may evoke images of a rumbustious night out filled with exotic drinks and highjinks followed by a morning waking up in possession of a traffic cone, the acquisition of which has somehow escaped the wreckage of your short-term memory.
If this is the case, you may be a tiny bit disappointed. This is all about how to play and rip DVDs and Blu-rays on Ubuntu.
Whilst that may not sound like quite as much fun, it’s less to leave you with a raging hangover. It should however, enable you to enjoy your video on your OS of choice.
What cocktails and traffic cones have to do with all of this will become apparent shortly.

What I’m going to cover here is :

  • How to Decode and Play DVDs using VLC
  • How to Convert DVD and Blu-ray files to mp4 video using Handbrake
  • How to Transcode DVD and Blu-ray discs to Matroska (mkv) format using MakeMKV

This should give you all of the steps required to watch and – if required – copy movies, tv shows etc from an optical disc.

First of all though…

The Legal Disclaimer
The legality of ripping copyrighted material differs across jurisdictions. You may want to check the situation where you are before you follow any of the steps detailed in this article.

Whilst we’re on the subject of disclaimers…

The Taste Disclaimer
The subject matter at hand means that there is a strong temptation to include quotes and (possibly) oblique references to movies here and there. Of course I wouldn’t dream of stooping so low just to get cheap laughs…much.

Oh, one more thing…

Efficacy disclaimer – The steps described here will work most discs. In the rare instances where this is not the case do not seem to follow and discernible pattern.
For example, the same steps to persuade a dark comedy to present you with a Marmalade Sandwich (in mp4 format), may cause a loveable cartoon bear to fix you with a stare that’s harder than a coffin nail.

Moving swiftly on…

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You have chosen not to trust… – Citrix Receiver and SSL error 61 on Ubuntu

After months of trouble-free operation, Citrix Receiver decided to wreak some havoc one morning last week.
Connecting to work (using Firefox on Ubuntu and Citrix Receiver for Linux 13.8) was trouble free as usual.
However, when I then tried to select a PC to remote into, Citrix informed me that …

“You have chosen not to trust Entrust Root Certification Authority – G2. SSL error 61”

At that point, I reflected that what I knew about Citrix and SSL certificates would fit on the back of a fag packet.
After some intensive “research” it should now fit into a short blog post…
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Streaming Videos with Plex on Raspberry Pi

The recent Bank Holiday weekend in England provided me with a perfect opportunity to get on with some D.I.Y.

We have a collection of movie files, which I’ve stored on an external USB hard-drive. At the moment, these files are only accessible from the smart TV it’s plugged into.
I want to be able to stream these movies to the various Connected Devices we have around the house.

Time, once again, to call on my trusty Raspberry Pi 2 b-spec, running on Raspbian Jessie.

What I’m going to do is :

  • Mount my USB Drive on the Pi
  • Install Plex Server on the Pi to facilitate streaming
  • Install Plex Client on relevant Connected Devices
  • Create a Library containing all of my movies
  • Stream a movie whilst I wait for it to stop raining

Hopefully after all that, I’ll be looking at something like this :

plex

Before we do any of that however, we need to get the USB drive to work on the Pi…

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