Linux bootable USB drives on Mac OS X Yosemite – Solved!

bootsIn my twenty plus years of working on PCs, I have seen external media formats change from 5.25 inch floppy disks (which really were floppy) to 3.5 inch (not-so) floppy discs to CD to DVD and USB (thumb) drives. I’ve had PCs at one time or another that have used all of those formats, but over the past couple of years, the push has to been to move away from external media whenever possible. Thus the last two PCs I have purchased did not come with anything other than USB slots. One is my ZBox computer that I use for development, and I change operating systems on it fairly frequently.

Rather than burn a DVD of an ISO every time I want to reconfigure the development box, its should be easier to make a boot-able USB. Using Windows there are a host of different GUI tools to create bootable USB drives, and most Linux distributions are similar. If you are on a Mac running OS X Yosemite, the  solution isn’t quite as simple. A number of websites include directions, but generally I’ve found they don’t work.

But this week, I found a successful method, and created both Fedora and CentOS bootable USB drives (unfortunately it doesn’t seem to work with Windows ISO’s). Because this requires enabling the root user account on your system, be sure to exercise caution when following these steps. Read on for more information.

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Check for multiple files in Pentaho Kettle – Control Flow components – Part 3

arrowsA couple of posts back, I covered how to use the control flow component – “File Exists” to look for a file, and if its not found, to take appropriate actions. While useful, that component does have the limitation that it only looks for one file. If you need to check for multiple files on the local machine or somewhere on your network, you can use the “Check if files exist” component instead. This comes in handy if your workflow requires more than one file, or if different actions can be taken if a file is missing or not.  Below I’ll walk through creating a simple workflow to illustrate the usage of this step.  Continue reading

Wait for a File in Pentaho Kettle – Control Flow components – Part 2

In my last post I wrote about checking for the existence of a file as a control mechanism in a Pentaho Data Integration (aka Kettle) job. This time around, I look at a similar component in Kettle, but this one waits for a file for a specified time. It will make repeated checks to see if the file has appeared, pausing between each check.

While the two components have similar functionality, they also have some marked differences:

  • “File Exists” is most useful at the beginning of a job flow, and the “Wait for File” process can be useful in multiple places within a job flow.
  • “File Exists” can access multiple file systems such as HDFS, Amazon’s S3 and the local computer and network and  “Wait for File” can  only access the local computer and network.

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Check for a file in Pentaho Kettle – Control Flow components – Part 1

fileexistsWhile working on a recent ETL project at my day job, I needed to include a step to check for a file before processing could begin. Pretty simple concept, but one which the tool I are using doesn’t have. You have to write an external code snippet (in one of two languages), and then call that code from within the job. It just re-enforced for me why I like Pentaho Data Integration. Below I’ll demonstrate how you can look for a file in Kettle, and quit the job if the file isn’t found, easily with no external code.

In Kettle, both the transformation palette and the job palette have a FileExists component. The Job palette also includes a component to check for multiple files. In my case, I needed to check for one file for job control purposes, so this example will demonstrate that process.

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