Changing the Hostname and IP Address on a CentOS server and re-configuring Oracle and ORDS

I use VirtualBox quite a lot. Rather than going through the rigmarole of installing the software I need every time I want a new environment, I simply clone the VM I’ve already installed everything on.
One drawback with this approach is that, because I’ve already configured the network settings on this baseline VM, I can’t run two clones concurrently as they both have the same hostname and IP address.

What I’ll be covering here is :

The approach I’ve taken is to execute each step on the command line without the need for any interactive input. Therefore, it’s possible to take the steps described here as building blocks for a bash script (or scripts) to accomplish these tasks.
The exception is where I edit the contents of files. If you wanted to automate this, you can use something like…

sed -i s/192.168.56.220/192.168.56.225/g file_to_edit

…for the IP address and…

sed -i s/frea./rincewind./g file_to_edit

…for the hostname where file_to_edit is the file you want to change.

If you’ve found your way here in search of simply changing the hostname and/or the IP address on a CentOS7 server, then you can just skip all the database related stuff and start right here.

By the way, I’ve decided upon a new naming convention for my servers which makes use of Discworld characters. There may be the odd reference to this in what follows…

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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

Oracle Instant Client on Ubuntu…with added Aliens

“This is the voice of the Mysterons…have you got any Lemsip ?”
Yep, I’ve caught Deb’s cold and now sound like the alien menace from Captain Scarlet.
This provides a somewhat tenuous link to the subject at hand – namely installing Oracle Instant Client on Ubuntu.
I think I’d better explain. As you probably know, Ubuntu – being a Debian based Distro – uses the Debian packaging mechanism. Oracle, on the other hand, provides Instant Client for Linux in rpm ( RPM Package Manager) format. In order to bridge this divide, we’re going to need to use the alien utility. Look, I did say it was tenuous OK.

I’m doing this on a 32-bit Ubuntu installation ( 10.04, since you ask). If you’re running 64-bit, you’ll need to download the appropriate equivalent files. Continue reading

Oracle Client on Ubuntu – Installation and Configuration

Having obtained a sick laptop and nursed it back to health ( i.e. installed Ubuntu 10.04), I’ve decided to do something a bit more useful with it.
I want to be able to connect to the Oracle 11g database on my server. This means, installing an Oracle Client.
I’ll be using the machine mainly for SQL*Plus ( although I may well be installing SQLDeveloper shortly). Therefore, rather than mess about downloading the client directly from the Oracle site, I’m going to use the XE client, which is available in the Oracle supplied apt package repository.
NOTE – if you simply must have the full Oracle Instant Client, then you can find details of that installation here.
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Troubleshooting Oracle 10g XE Installation on Ubuntu

You’ve followed the instructions, everythings working fine. You shutdown your machine and go for a celebratory pint / cup of tea / curry.
Then, when you next start your machine, Oracle doesn’t want to know. What’s going on ?
To be honest, I don’t know. What I do know is that there are some steps you can take to at least attempt to diagnose your problem.

Before I go any further, I’d like to dedicate this post to Wayne.
He found himself in this position. After much head scratching between the two of us, he managed to find and resolve his problem.

Whilst a hardened veteran in computing terms, Wayne was new to both Linux and Oracle. From the mails I’ve received regarding this post, there seem to be a number of people in a similar position to him. Therefore, this post is written with these interpid souls in mind and I’ve tried to take time out to explain why we’re doing stuff at each step.

Update

It’s now quite a while since I posted this and some people have contributed some really useful comments. These include solutions that they found to various problems, which are additional to the ones in this post. So, if you’re still having problems, check out the comments as well. MestreLion’s tip about sudo chmod -t /var/tmp/.oracle seems to be a particularly good example of this.

One other point worth mentioning is that Oracle 11gXE is now available. Many of the issues in this post are still relevant. However, if you’d like to know how to install the latest XE on Ubuntu or Mint, here are the instructions
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