via feeds.gawker.com
Wednesday, November 25, 2009
Saturday, November 21, 2009
Saturday, November 14, 2009
Dumb things to check (from whatexit.org)
a list of dumb things to check
found at whatexit.org
- Is the filename extention right? Should it be .php instead of .html?
- You can get to the web site? Are you working in "off-line" mode?
- Make sure CapsLock is off. (Same for ScrollLock and NumLock)
- Is there a (invisible) CTRL-M at the end of each line in the text file?
- Does the text file end with a newline?
- Are both ends of the (power/network/video/etc.) cable plugged in?
- Did you unplug and re-plug in the cable to make sure its in right?
- Is the cable plugged into the right jack? (Some jacks look the same: AUI and video, Some Sun's have a 'stealth' video jack that you aren't supposed to use, etc.)
- "Did you get permission to run crack against that password file?" ... "Is it in writing?"
- Is the user pressing RETURN when you think they are? (Are they pressing it at all?)
- Is the user typing a "/" or a "\"?
- Does the user know which is the lessthan and which is the greaterthan symbol?
- Is the screen paused via Ctrl-S? (press CTRL-Q to find out)
- Does your test gear test what you think it tests? What happens when you run the exact same test on a known-good and a known-bad element? Do you get the results you expect both ways?
- Does plugging a lamp into that outlet make it light up? (If you use a radio, be careful of radios with battery backups)
- Is the laptop running off battery? (therefore obscuring a power problem)
- Use cut-and-paste to copy that variable name (or URL, commmand line, etc.) to see if it was entered correctly.
- Check the file permissions.
- Check the environment variables (Use "strings" on the binary to find out what they really are supposed to be).
- It's too easy to answer "yes" when asked, "Is it plugged in." It's better to ask them to power it off, then power it back on OR ask them to "check both ends of the power cable" OR ask them if the power light is on, off, or blinking. (and if it's blinking... RUN!)
- Type it again (without using cut-and-paste) and see if you get the same results. (good way to find a typo)
- Is the default route set? Is the netmask set correctly?
- Traceroute from A to B. Traceroute B to A. Do they match up?
- Is someone else also at that IP address? (Unplug the network cable and ping the address)
- Are you really on the host you think you are?
- Is the program reading the last line of the file? Is it being processed right?
- Are you doing the test from the right machine? Would the test be more effective from a different machine?
- (firewall ruleset issues) If you move the machine to another IP address does it still happen? If you move the machine to a different subnet does it still happen? If you put a different machine at that IP address does it still happen? If you boot the same machine on a different OS (like a CD-ROM based Linux or FreeBSD) does it still happen?
- Does the same thing happen when you specify the IP address instead of the hostname? (Hint: the lmhost or /etc/hosts may be overriding)
- Is that a file, a directory, a hard link, a symbolic link, or a mountpoint?
- http://www.psc.edu/~mathis/MTU/index.html: Six classes of bugs limit network performance.
- packet losses, corruption, congestion, bad hardware
- IP Routing, long round trip times
- Packet reordering
- Inappropriate buffer space
- Inappropriate packet sizes
- Inefficient applications
- Are the binaries really the ones you think are running? (Did you install in single user mode when /opt wasn't mounted? Can you check the md5 or sha1 checksum vs. a machine that is running properly?)
- Is DNS configured right? Misconfigured DNS masks other problems and appears as bizarre problems that will send you looking everywhere except /etc/resolv.conf
- Is there a rogue DHCP server on the network messing with you?
- Is the device driver you're trying to install for the device you actually have?
- Did you remember to check this list?
Friday, November 13, 2009
Comet Hunter’s Last Look at Earth Is Haunting
This gorgeous image of a blue arc of the Earth against the blackness of space was captured by the Rosetta spacecraft as it swung by our planet.
The European Space Agency mission is on its way to intercept the comet, 67P/Churyumov-Gerasimenko. The ship will deploy a lander onto the comet’s surface, the first such attempt to be made.
To gather up the necessary energy to reach the comet out past Mars’ orbit, Rosetta needed three swings past Earth. This is its third and final flyby. It will reach the comet in early 2014.
Unlike the most famous pictures of Earth, which show most of the blue marble, this photo presents a planet in darkness, just the South Pole awash in light.
Image: ESA. High-resolution image of planet Earth from Rosetta.
See Also:
- Out of the Blue: Islands Seen From Space
- Stunning Views of Glaciers Seen From Space
- Asteroid Impact Craters on Earth as Seen From Space
- Erupting Volcanoes on Earth as Seen From Space
- First-Ever Asteroid Tracked From Space to Earth
- Time-Series Photos From Space of Aral Sea Death
WiSci 2.0: Alexis Madrigal’s Twitter, Google Reader feed, and green tech history research site; Wired Science on Twitter and Facebook.
via feeds.wired.com
Wednesday, November 11, 2009
Monday, November 9, 2009
codinghorror.com; Whitespace: The Silent Killer
So true it's scary via codinghorror.com
Whitespace: The Silent Killer
Ever have one of those days where everything you check into source control is wrong?
Also, how exactly is that day is different from any other? But seriously.
Code that is visible is code that can be wrong. No surprise there. But did you know that even the code you can't see may be wrong, too?
These are the questions that drive young programmers to madness. Take this perfectly innocent code, for example.
Looks fine, doesn't it? But hold on. Wait a second. Let's take another, closer look.
OH. MY. GOD!
If you're not a programmer, you may be looking at these two images and wondering what the big deal is. That's fine. But I humbly submit that, well, you're not one of us. You don't appreciate what it's like to spend every freaking minute of every freaking day agonizing over the tiniest details of the programs you write. Not because we want to, you understand, but because the world explodes when we don't.
I mean that literally. Well, almost. If one semicolon is out of place, everything goes sideways. That's how programming works. It's fun! Sometimes! I swear!
We got into this industry because, quite frankly, we are control freaks. It's who we are. It's what we do. Now to imagine, to our dismay, that there's all this stupid, useless whitespace at the ends of our lines. Stuff that's there, but we can't see it. Well, those are the nightmares OCD horror movies are made of. I have a full-body itchiness just talking about it.
Depending on how far down the rabbit-hole you want to go, there's any number of things you could do here:
- Have a post-build step, perhaps something with a regular expression like
\s*?$in it, that auto-cleans extra spaces checked into source control- Execute a local macro which removes whitespace from ends of lines
- Have a special rule to highlight extra spaces
- Run your IDE in whitespace-always-visible mode, or toggle it frequently
OK, fine, so maybe the world won't explode if there are a few extra bits of whitespace in my code.
But all the same, I think I'll go back and make extra double plus sure no more of that pesky whitespace has accumulated in my code when I wasn't looking. Just because I can't see it doesn't mean it's not out to get me.
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Posted by Jeff Atwood View blog reactions
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