Karthik’s digital footprint

vi editor : the ultimate cheat sheet

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For beginners in UNIX, vi editor  is a source of frustration. Typically users being their UNIX journey with vi, give up on it in the first week or two and flee to emacs, pine and other sort of editors.

For Command Mode type   “Esc”

For Insert Mode   type       “a”

For Visual Mode    type       “v”

For Line Mode       type     “:”

you wanna ….
this is how u do it notepad
this is how you do it in vi
type text just type insert mode + type
undo NA
command mode + u
move your cursor up left down right use arrow keys insert mode + use arrow keys
page down use page down key
insert mode + use page down key but if this doesn’t work try ctrl f
page up page up key insert mode + page up key but if this doesn’t work try ctrl b
delete character
delete  key
insert mode+ delete if it doesn’t  work go for command mode + x
backspace backspace insert mode + backspace
highlight some area use mouse visual mode + use cursor
copy the highlighted text highlight the area with the mouse and press ctrl c to copy highlighted area visual mode + use cursor to select the area that needs to be copied and press ‘y’ key
cut the highlighted text
delete the  highlighted text highlight the area with the mouse and press the delete key to delete the highlighted aea visual mode + use curor to select the area that needs to be deleted and press ‘d’ key
paste what ever is in the clipboard ctrl v p
find text ctrl f  … type the text in the find window… /text    or ?text
quit file line mode + q . If no changes it will silently quit. Other wise   it  says use q! or wq
quit file without saving changes just close the window …. line mode + q!
quit file by saving changes ctrl s + close the window line mode +wq

Written by Karthik Reddy

August 14, 2009 at 3:08 am

Posted in Uncategorized

VMware windows xp image does not boot

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Warning: the system was unable to load a page of memory; this can be caused by network problems or a failing hard disk drive.

VMware Workstation unrecoverable error:(vcpu-0)

Exception 0xc0000006(disk error while paging ) has occured

A log file is available ………………………..

 

For anyone who regulary uses VMware a message like this is can be very disturbing ; and so it was for me earlier today when I was just routinely trying to boot up my windows xp image. The image would not boot up and a error window  bearing the aforementioned mambo jambo would pop up. 

I am not really sure what is going on here; but if I were to guess it could be that the hard disk space  the image  is present in is possibly corrupted.

Thanks to one my friends, here is a fix:

Go to the VM console and look for a option called “Clone this Virtual Machine” . Click this and it will open a wizard for you. You are basically using this wizard to create a copy of your image (aka VM) into another location on the hard disk that is hopefully not corrupted.  Breeze past the next few screens of the wizard that popped up  and make sure — this is very important — that you select a new location on your hard disk for the copy of the image  that is going to be created. A safe idea is to create a folder , by name say “MyImage Copy” in  a folder that is not at all related to the folder structure of your corrupeted image . Once you are through with the wizard and a good 20-40 minutes later –it should take around 20 to 40 minutes or possibly more depending on the size of your VM to do the ‘copying’  or ‘cloning’– you should notice that the “MyVM Copy” folder now has all you need to start(or boot) the image afresh. Of course, the state of your image should be identical to what it was when you last opened it .

BTW you can now delete your old corrupted image.

Written by Karthik Reddy

May 26, 2009 at 8:17 am

Posted in Uncategorized

Using a calling card got a little more easier, thanks to iPhone

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As many of you may know, calling cards are typically used to call overseas at cheaper rates than what ISD calls would offer. I use these cards frequently to call my friends and family in India.

For all the impatient folk that are tired of listening through the lengthy messages and pressing a lot of keys on the cell phone while using these calling cards to call someone, here is a tidbit.

iPhone gives you an option to store the phone number of a contact along with the toll free number of the calling card provider .This means you don’t have to press the recipient’s number every time you call him/her. You create a contact and assign it the recipient’s number along with the toll free number. Once you store this composite number you can directly call this number in the iPhone-esque way of feather-touching it and iPhone takes care of pressing the keys for you.

Let me use an example to drive my point home.

For example if the toll-free number of the calling card is 1-866-123-1234 and the number you wanna call is 8611234567, you can create a contact and assign the contact, the following number : “18661231234,918611234567″ ; 91 is the international code of the country, in this case it is India . I am assuming that you have your phone registered with the calling card provider so that you do not have to press the access code; only few calling cards provide this option. If not, the sequence, “18661231234,123123,918611234567″ would do; 123123 is the assumed access code. Now, all you have to do is to dial this stored contact in the iPhone-esque way of feather-touching it.

The question on your mind at this point might be about the location of the “,” character on your iPhone keypad. You can find a key that has the characters “+*#”. Press that key and you will notice the change of the keypad style. The new-style keypad has a “pause” key. Pressing this “pause” key would introduce ‘,’ character. The ‘,’ character results in a unit delay between the preceding and the succeeding number. If you had decided to introduce two units of delay you would type in two commas; your number now looks like 18661231234,,918611234567.

As few of you might have already noticed , this method of storing numbers can also be used to store telephone numbers with extensions , and thereby avoid the repeated labor of manually typing the extension numbers .

Written by Karthik Reddy

May 4, 2008 at 5:26 pm

Posted in Uncategorized

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Tata Indicom wireless data card : to avoid or to embrace

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The following is my experience with the Tata Indicom’s wireless data card , in Bangalore:

The sales pitch for this TATA Indicom card was that the minimum speed would be 140 kbps and that the installation of a “speed optimizer” software, provided on a CD , would jack up the minimum speed to 250 kbps. Well , complete bull.

In spite of being skeptical, I decided to buy the data card and gave it a shot . I installed the drivers including the “speed optimizer” and measured the speeds using the “speed meter” tool available on 2wire.com. The speeds fell in between 25 kbps and 70 kbps(thats kilobits , not kilobytes) in the morning and afternoons, and between 80 kbps and 100 kbps in the evenings.

To put this in perspective for the US internet consumers, Comcast’s cable internet plans priced around 30 to 40 dollars a month in US measured up to 4 to 5 Mbps when tested using the same “speed meter” tool.

To give you a feel of what kinda effect , speeds between 25 kbps and 70 kbps could have on one’s browsing experience , I am listing few web page load times I have myself measured :

46.2 secs for yahoo.com

40.7 secs for digg.com

8 secs for google.com

10 secs for timesofindia.com

29 secs for techcrunch.com

17 secs for logging into gmail.

To be fair to Tata Indicom , I was told that the data cards offered by other Indian telecom providers like Reliance and Airtel fare no better ; but I can not confirm.

Bottom Line: Go for the Tata Indicom data card only if you are comfortable with the aforementioned speeds and also if you are really desperate for some portable “internets” .

For those of you interested in the Tata Indicom’s data card: it costs around 2800 INR upfront and then a monthly rental of 100 INR . You will be given a USB compatible device , that acts as the transceiver of the data , and you will get to keep it.


Written by Karthik Reddy

May 4, 2008 at 12:10 pm

Google tries to burst Amazon’s bubble

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The on-the-face-of-it reaction to the title of this post  might be to wonder whether Google made a foray into retail business or whether Google tweaked its search algorithm to reduce Amazon’s page rank. Neither. Google has done something more worrisome and troubling to what has been until now, Amazon’s highly prospective cash cow i.e., S3+EC2+SimpleDB combo of web services.

Google has just announced the release of a new product called GoogleAppEngine(GAE) that competes directly with Amazon’s S3+EC2+SimpleDB stack of web services . This kinda product from Google is definitely few years overdue, given the innovation and leadership standards Google is more often held to.

Amazon released S3 two years ago and then EC2 and Simple DB subsequently. The world was kinda surprised to see the innovation and leadership on the fronts of Cloud Storage and Cloud Computation, come from an unexpected entity, i.e., a multi-billion dollar retail giant. To draw an analogy, imagine the reaction if Walmart in the 1960s came up with a state-of-the-art aeroplane , of Jumbo Jet’s stature , even before Boeing did it. Well, it’s kind of an exaggeration. But I think I made my point.

As with any product Google releases, it’s brand name has so much value, the initial user adoption would be very high. If Google attached its brand name to a word processor that was used in the early 1990s and lionized it in a press conference , that would be good enough for a good number of users to give it a shot. So, the question is whether this sort of brand value of Google’s is good enough to cut into the head start Amazon’s S3+EC2+SimpleDB already has.

I skimmed through GAE’s features and tried to judge the prospects the product holds for website owners, developers etc. I should say I was impressed. I will go into greater detail about my findings including the technical nitty-gritty and the economics of the product in a later post , but if I have to pass my verdict on whether Google AppEngine is going to attract people away from the Amazon’s S3+EC2+SimpleDB stack, my verdict would be a ‘Maybe ‘ . I know, a ‘Maybe’, doesn’t mean much, but I am in a tough spot here.

Both the products in their current form and shape have their vulnerabilities. Amazon’s Achilles ’ heel is their still-nascent Simple DB and GAE’s vulnerability is the fact that the platform is not open – by that I mean that as a website owner one can not install any third party applications. I should also note here that Amazon has been awfully lethargic in adding new features to their SimpleDB product. Just wanted to get that on the record!!!!

On the contrary, Amazon’s strength lies in the openness of EC2 component and GAE’s significant strength is their BigTable. So, if Amazon can start working on adding new features to SimpleDB and do it fast, like really fast, I think it can hold off users from giving GAE a shot. Similarly, if Google can work on making their GAE as an open platform it could surely give Amazon a run for their money.

Whether it is Google or Amazon that ends up staying on top in this game , the consumer wins , as the respective product teams at Google and Amazon try to one-up each other . The smooth sailing for Amazon in this space has just come to an end.

Written by Karthik Reddy

April 8, 2008 at 7:42 am