It just kills me when I type git commit or some other such command on a newly configured machine and up comes nano or (worse!) pico. And, I so infrequently have to do this that I can never remember it - so, for posterity:
To set your default editor (to Vim) on Ubuntu:
update-alternatives --config editor
$ sudo update-alternatives --config editor There are 4 choices for the alternative editor (providing /usr/bin/editor). Selection Path Priority Status ----------------------------------------------------------- 0 /bin/nano 40 auto mode 1 /bin/ed -100 manual mode 2 /bin/nano 40 manual mode * 3 /usr/bin/vim.basic 30 manual mode 4 /usr/bin/vim.tiny 10 manual mode Press <enter> to keep the current choice[*], or type selection number: 3
UFW is a pretty simple to use firewall wrapper for Ubuntu. Recently, I have been using it to block spammers on a little service I run for the Nashville Tech community. I used to do this with iptables directly, but this is far simpler.
Here's a quick primer on firing it up and blocking a particular IP address. It's disabled by default so you need to allow your services and then turn it on:
ufw allow ssh/tcp ufw allow 80/tcp ufw logging on ufw enable ufw status
Order matters - once a rule is matched the others will not be evaluated. So, to block that IP, you need to insert it early:
ufw insert 1 deny from 188.8.131.52/24
Here's what these rules look like:
# ufw status Status: active To Action From -- ------ ---- Anywhere DENY 184.108.40.206/24 22/tcp ALLOW Anywhere 80/tcp ALLOW Anywhere 22/tcp (v6) ALLOW Anywhere (v6) 80/tcp (v6) ALLOW Anywhere (v6)
And you can number the output to make it easy to clean up or delete your rules:
# ufw status numbered Status: active To Action From -- ------ ---- [ 1] Anywhere DENY IN 220.127.116.11/24 [ 2] 22/tcp ALLOW IN Anywhere [ 3] 80/tcp ALLOW IN Anywhere [ 4] 22/tcp (v6) ALLOW IN Anywhere (v6) [ 5] 80/tcp (v6) ALLOW IN Anywhere (v6)
To delete one it'd be ex:
ufw delete 1
I came up with a few new years resolutions. In no particular order:
The image below is an example of solargraphy. A pinhole camera is used to take a picture over 6 months. This photography technique perfectly illustrates the position of the sun between the summer and winter solstice.
Trying to decide where to place some skylights in my garage renovation project, I needed to simluate the look. I took pictures of the one installed skylight from the perspective of the camera if it was installed in 2 places, and splicing them into a 'blank' image. Result:
I decided to go with #2. Aside from the exposure and the skylight being open, very accurate!
I gave a presentation tonight at Nashville Girl Geek Dinner's Code & Pinot event. We went over some UNIX history and did a bit of command line intro. Action shot:
It was a great event! I had a lot of fun teaching something I'm passionate about (while de-rusting a bit on relating the basics!) and had some great conversation afterwards. I've given the history talk a number of times over the years, but the GGD Nashville crew got to experience my first test of this talk with slides! \o/ You can download my history presentation here. And here is the history of what I typed during the UNIX lesson.
Side note: We discussed the historically famous "Space Travel" game (look it up). But, all I knew was that it was a game...and I'm not a gamer. So, I had to look it up a bit more when I got home. Apparently it let you simulate travel between planets in our solar system and cost about $50-$75 in 1969 money to play a round on the GE 645 running MULTICS! Which is $320-$482 in 2015 money. No wonder re-writing the whole OS on cheaper hardware was worth it. :-P
If any of you were there and would like to know more, here are some good links that I used when re-acquainting myself with UNIX's colorful history and some beginner material:
Don’t have UNIX to play with? Get it in the browser with JS/UIX! http://www.masswerk.at/jsuix/
Trey came to town. So, we had beer. And I made picturefilms. Used a GoPro and the Radian, which had arrived a few days before. Still not great with it, but the results here were fun. Filmed at both Craft Brewed and M.L. Rose. Approximately 250X normal speed.
I thought I had a decent understanding of physics. But after reading this, someone should revoke my 'amateur scientist' card. This (from Wikipedia) helped me understand it:
Since we started with over half the atoms in the spin-down state, initially this drives the system towards a 50/50 mixture, so the entropy is increasing, corresponding to a positive temperature. However, at some point more than half of the spins are in the spin-up position. In this case, adding additional energy reduces the entropy, since it moves the system further from a 50/50 mixture. This reduction in entropy with the addition of energy corresponds to a negative temperature.
This is not about the common notions of hot and cold, this is thermodynamic temperature, which is about entropy and energy. OK, so to me, this amounts to a neat physics trick. The universe will not collapse and our understanding of physics hasn't changed. Hopefully, it'll inspire a few folks (like me) to understand it better. Doing more reading, it reads like this only works in a 'system' of atoms, not with a singular atom. If you can't make a single atom colder than 0.0 kelvin, then the fundamental physics models don't change. Somewhat frustratingly, I see no mentions of anti-gravity, which was the most radical thing said on the nature.com article. So, please erase that and any anti-gravity belt predictions from your memory banks.
Speaking of theoretical maximums, another fascinating one is the concept of "absolute hot", which is currently defined as the Planck temperature, (1.416785×10^32^ kelvin). All physics models break down, even things like gravity. And, theory says that the entire universe has already experienced this temperature, a fraction of a second after the big bang. Enjoy that thought.
Went to the datacenter last night to build out a few DB servers with 64GB of RAM. And set up a timelapse to record parts of the work. Marc, Brian and I did 2 servers each. You can see some up-close shots of the Dell R710 hardware, though it's quite blurry. Playback is 74 x normal speed.
Found a paper wasp nest today while we were having work done on the house. It was cold out and I thought they were dead...when I set it down in the sun to take a picture, I saw some movement. So, I filmed the little guy trying to get out. National Geographic here I come.