Archive for May, 2009

Useful Tools

May 25th

Posted by John in thoughts

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I use several online tools that make my life easier, and I’d like to share them in the hope that they make someone else’s life easier.

Readability
Readability is a bookmarklet that reformats your current page and makes it readable. It’s a wonderful tool in the world of web pages full of ads and useless junk.
Mint.com
Mint.com is a free online service to keep up with your finances. It offers a quick way to see where all of your money goes and shows where you can save money of get better deals (on bank accounts, credit cards, etc).
Nike+
Nike+ is a two-part service that allows you to keep track of running or walking with ease. The first part is the accelerometer you put in your shoe that connects to the receiver plugged in to an iPod. This records the run and offers real-time feedback during the workout. The second part is the website that keeps a history of your runs and allows you to compare and compete with the millions of other Nike+ users. The only non-free service on this list, the Nike+ will set you back $30 (assuming you already have an iPod nano or touch).
Print What You Like
Another free bookmarklet, print what you like allows you to selectively print sections of webpages without all of the cruft. Although I don’t print web pages very often, this tool is very helpful when I do.
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Friday fun at work, part 2

May 8th

Posted by John in programming

2 comments

I finished something up at work today that I have been working on part-time this week. My boss really likes it, and I’m pretty happy with how it turned out. I call it attachment scrubbing.

Last week, a friend and I were talking over lunch about some email woes our company was having. Specifically, some people were emailing around some large attachments, and they were putting a lot of strain on our mail server. By the time we finished eating, we had come up with the idea of putting something in place on the mail server to intercept attachments from emails. A user can send an attachment as usual, but when it gets to the email server, my program grabs it. I remove the attachment from the email, upload it to a web server, and put a message with a link to the attachment back in the email. When the recipient gets it, their email program won’t choke on some large file, and our servers are happier because we will only be storing one copy of the attachment for each message.

The real beauty of this system is that the user sending the email doesn’t have to do anything differently. And although the idea didn’t come from a desire to make external users happier, it can make their email experience more pleasant by not clogging up their inbox.

This was pretty fun to work on for the past week and a half, and it provided an interesting diversion from some mundane system administration I’ve had to do lately. I now have a lot more understanding of how my company’s email system is set up, and I think I could set up a similar system pretty easily. Email servers are pretty complicated, but there is nothing like installing your own and customizing it that will teach you how it works.

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A little puzzle

May 6th

Posted by John in thoughts

4 comments

I was listening to NPR on the way home today when a story about college entrance essays got me thinking. How do admissions officers judge the merits of an entrance essay? Is it based on some fixed scale? I can’t imaging that something as subjective as an essay can be effectively judged on a fixed scale. Is it judged relative to the other essays? This makes more sense to me, but I don’t understand the logistics. So I thought of a simpler problem that has the same elements, but is easier to identify with.

Suppose I were to come to you and offer you 100 boxes. In each box is a random amount of money between $0.01 and $100. After each box is offered to you, you must decide to keep it or to return it to me. If you return it to me, I will show you the amount of money in the box, but you will never see it again (and you won’t get the money). You are allowed to keep the first 10 boxes you choose. If you have not taken all of your 10 boxes by the time I offer the last boxes, you must take the remaining boxes to round out your total of 10. When you pick your tenth box, I will not offer any more boxes. What strategy optimizes your earnings?

Or suppose you are in a fishing tournament. At the end of the day, you must weigh in with your 10 biggest fish. If the game warden catches you with more than 10 fish in your boat, you will be disqualified from the competition. What strategy will assure your highest total weight?

More adventures of home tech support

May 2nd

Posted by John in home storage

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Recently, Karen’s laptop refused to boot. After a few attempts to fix the problem (OS X’s Disk Utility and Disk Warrior), I connected the drive to my computer, made a complete backup, and reformatted it. This is the first time I have ever had to reinstall OS X on any Mac I have owned. I suspect her problems were caused by bad sectors on the disk, so before I reinstalled the operating system, I erased the disk by writing zeros to the entire disk. This way, if bad sectors are detected, the drive could substitute them for the good sectors it keeps in reserve.

After reinstalling the OS, she reinstalled her programs, and I restored her documents from the backup. The last thing too do was to connect he back to our home file server.

Originally, I used NFS to share our files. When I reinstalled her OS, though, Karen’s user id reverted back to the OS X default. Unfortunately, this was the same user id that I used on my computer. Because NFS based its permissions on the client’s user id, I had two choices. One, I could change her user id on her fresh install. Or two, I could use something other than NFS on the file server.

The second option seemed to be a better long-term solution, so I looked in to setting up SMB. SMB has the advantage of requiring a user id and password to connect. This means that from any computer, no matter the users on that computer, I can connect to the file server with the proper permissions.

Setting up the new network shares turned out to be less painful that I anticipated, and, for now, all is right in the world of our home computers.

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