Linux

In my previous post regarding PerlCatalyst tutorial setup I mentioned about setting up a virtual machine inside a virtual machine. I didn’t provide you with much information regarding how I did it because all the tutorials related to that is already available online. Pasting the links below: Catalyst::Manual::Tutorial::01_Intro But I had a serious problem with my virtual box inside a virtual box. Not so serious actually, just that it stopped me from proceeding ahead because of my ignorance of network configuration. The tutorial says that after downloading the virtual machine for the tutorial and setting it up as mentioned in the website, I could start using it as a server and log into it using ssh from my host computer. But for some reason the VM (virtual machine) provided by Catalyst just had a loopback network configuration. It wouldn’t show me a proper ip address to which I could connect to. And hence I had no way of connecting to this new tutorial virtual machine that I started from within an Ubuntu Virtual machine. I played around with the network configuration of VBox for a couple of hours trying out the different settings provided: ...

Over the past few years, the only text editor I’ve been using on Linux is emacs. Not because I wanted to. But after I joined the firm that I currently work for, I was trained in emacs. And I found it difficult to use initially. But then I decided that if every one else in the firm could use it and become an expert, then so can I. So I spend some time with the built-in emacs tutorial and I just learned it really quick. ...

So in one of my previous posts I told you about terminal multiplexing and also mentioned how cool it was. Now is the time to introduce you to GNU Screen. The wikipedia page is a good introduction already. But I should talk about it from my point of view, about how I use it. To be honest, if I knew of the abilities of tmux at the time I got to know about screen, I would have just started using tmux. It isn’t too hard to switch though. It would just take a day or two of getting used to the new short cuts. Or you could go ahead and manually configure your shortcuts to keep you happy. ...

Hello there folks! I have been using [BASH](http://en.wikipedia.org/wiki/Bash_%28Unix_shell%29) for quite a long time. Yet I feel like there is a lot that I don’t know. The irony is that I am doing the BASH and Linux Basics training for new hires at my firm. I am not that bad, you see. It is just that there is so much to know. And I am never happy with what I know. ...

I don’t know if you have even heard of this operating system named OpenVMS by HP. Unfortunately or maybe fortunately I have had a chance to work on it. The operating system has a cool feature, file version is built into the OpenVMS file system. But the problem with this is that if you go into a log directory and list out files, the list could get really long. I was just trying to make it display things that I usually use on Linux. ls -lrt ...

Hey if you have worked on Linux then you have interacted with bash. Maybe not. But it is mostly likely that your default shell is bash. I’m not surprised. I’m among the few people on this planet who regularly interacts with cshell also. Thanks to the kind of work I do. One great feature of bash that I miss in cshell is: Functions. Surprised? Cshell doesn’t support functions. It doesn’t have any concept of function. If you wanted to simulate a function, you have to write another cshell script that does what your function would do and define an alias that calls it. ...

I work on CSHELL these days. Probably the most unpopular shell today. Anyone would recommend not to use it. Because of the absurdness of its syntax and quoting. For an example: Top 10 reasons to avoid using CShell My intention was to write a generic wrapper script that I could use to invoke another script that supposedly attempts to update a database and in the unlikely event of failing to do so, the wrapper would wait for a while and retry again. I thought of this approach as we had been facing some database locking issues and some data that was supposed to updated wasn’t getting updated. And this was causing even more problems for us. Since some of our systems rely on this data. By the way, to give you an idea of the locking problem, let me tell you, we have one MySQL database, that is updated by several processes running on 7 different boxes. Now you can understand the number of processes trying to access the database at similar intervals. ...

So I was doing my regular job, writing new queries to test out my team’s new databases on Vertica. And suddenly my senior manager sends out an email to all in the team asking an estimated disk space requirement for each of our work. I had to find out how much space the raw data files for a complete history that were used to load my databases occupy on disk. ...