Tips and Tricks for Installing Ops Center 12c R2 (PSU2)

In one of my old posts, I wrote a step by step guide to install Ops Center on Linux. I still get questions about installation, mostly about installing repository Database. So I have downloaded latest patch set version if anything has changed about installation, and decided to write tips and tricks to help Ops Center users. If you have read my previous blog, or you are already an Ops Center user, you may remember that Ops Center can create required Oracle users, and install Oracle Database by itself. You can see the Ops Center web site, that you need to follow My Oracle Support Document 1450669.1 to download to obtain Oracle Database 11g for Ops Center, and the MoS document says, you need to download files and put them into “/var/tmp/downloads” folder. I don’t know if these RPMs are still valid, the latest Ops Center seem to support So I recommend you to download Oracle (patch 13390677). You need to put the zips files into /var/tmp/downloads folder. After you copied files, the creation of users and setting up local repository database is totally automated by the Ops Center installer.

I always think that Ops Center is a very smart installer, and it can handle almost everything. On the other hand, instead of dealing errors/warnings while installing, I recommend you to use OCDoctor, a small utility to check prerequisites. Download the latest OCDoctor zip file, extract it and run it:

How to Install PostgreSQL 9.3 on Oracle Linux

For whom are not familiar with PostgreSQL, it is an open source object-relational database system. It has more than 15 years of active development and a proven architecture that has earned it a strong reputation for reliability, data integrity, and correctness. Like all other enterprise companies, we use different databases beside Oracle to lower the costs. We prefer PostgreSQL instead of Microsoft SQL Server, because it supports PL/SQL for some degree.

In this blog post, I’ll try to show how to install PostgreSQL using YUM. YUM (Yellowdog Updater, Modified) is an open-source command-line package-management utility for Linux operating systems using the RPM Package Manager. It handles library dependencies, so it’s the easiest and maybe the best way to install any RPMs. In this blog post, I’ll install PostgreSQL on Oracle Linux because I use Oracle Linux when I need a Linux OS, and its support costs are lower than Redhat Enterprise Linux. In next weeks, I’m also gonna blog about backup and replication for PostgreSQL, and maybe (not promising) blog about some key concepts of PostgreSQL such as MVCC, vacuum and vacuum freeze.

I assume that you can install Redhat or Oracle Linux. You may read my old post about installing Oracle Linux, hopefully it would be useful. Anyway, if our Linux server is ready, we can download and install Repository RPM for our server. Visit


Finding And Deleting Old Files (on Unix and Windows)

I needed to write short scripts to delete old files on a Windows Server. It’s a very easy task on UNIX flavors but the limited capacity of Windows command line made me worried. You can use a simple “find” command to find old files on UNIX. For example, the following command will be enough to find and delete files older than 7 days:

For the ones who are not familiar with the find command, I’ll try to explain its parameters. The parameter “-type f” is not mandatory but it will help you find only “files” (and filter out directories etc). The parameter “exec” lets you run a command for the selected files. The brackets are replaced with the name of the selected file. The plus sign (+) will make the command line is built by appending each selected file name at the end.

Unable to Register with Red Hat Network

We want to install Oracle E-Business Suite on Red Hat Linux 6.2. To be able to use RHN Repository to install packages, we tried to register our system but when we issued “rhn_register” we got the following error:

VirtualBox: Failed to Create Host-only Network Interface on Ubuntu Linux

After I installed Ubuntu to my Laptop, I began to install my favorite applications. Everything went smooth. One of my favorite application is VirtualBox. I’m big fan of it, and I use it on both Windows and Linux systems. All of my virtual machines are created on VirtualBox. So I installed VirtualBox, copied a virtual machine from my backup storage and just before run the virtual machine, I remembered that I need to set up IP address of the host-only network. I opened the network tab in VirtualBox settings and I couldn’t see any Host-Only networks (there should be one in default). So I clicked to “Add Host-Only Network” button and got a strange error:

I haven’t seen this error before. I have checked if “/dev/vboxnetctl” exists, and unfortunately it doesn’t. It’s obvious that the “vboxnetctl” file should be a part of VirtualBox software but it wasn’t there. One of the good thing of VirtualBox is, you can do everything using command line. So I tried to add host-only network using command line, and this time I see “a warning message” before the error: