John Stanfield dot com

UPDATE: I like vi more than Aptana now. Here’s how I use svn up to update a bunch of Rails sites, and then use vi to edit a file in each site:

for l in `ls -1`; do
  svn up ${l}/config/environment.rb;
  vi ${l}/config/environment.rb;
done

And when I’m done with my changes, I commit them all at once (sort of) with the same message:

for l in `ls -1`; do
  svn status -q ${l}/config/environment.rb |
    egrep '^M' |
      svn commit `awk '{print $2}'` -m "changed environment.rb";
done

One lovely thing about Ruby on Rails is the uniformity of the directory structure. All of my apps have pretty much the same files in pretty much the same folders. Today, I wanted to edit the environment.rb file in each of my company’s nine applications. Ugh, what a ton of mouse clicks digging through nine directory structures (note: I am very much into efficiency — every second counts, and manual repetitive tasks suck). I thought There’s gotta be a way to find all files named environment.rb and open them in Aptana. This command works! I can get my work done in seconds now instead of minutes! I use locate, which keeps a database of file names… I’ve found it to be faster than find.

The command below will first locate all files beneath the present folder (that’s what $(pwd) does) matching the regular expression /.*environment.rb$/ which means all files ending in environment.rb which will exclude any SVN files with similar names. Files that match that regular expression will be passed to Aptana, which will open any and all files passed in as arguments. Aptana will use an existing window if open, otherwise it will open a new one (precisely what I want!).

aptana $(locate $(pwd)/.*environment.rb$ -r)

It is the same as:

aptana /apps/app1/config/environment.rb /apps/app2/config/environment.rb /apps/app3/environment.rb

It’s much faster than:

aptana /apps/app1/config/environment.rb
aptana /apps/app2/config/environment.rb
aptana /apps/app3/config/environment.rb

And here’s a textarea to tinker, copy, & paste from:
aptana $(locate $(pwd)/.*yourfile.rb$ -r)

I always forget the syntax… Here it is:

su
mkdir -p /mnt/whatever/you/want
mount -t cifs //hostname/sharename -o username=user,password=pass /mnt/whatever/you/want

And without formatting:

The router at my office, a Linksys RV082, doesn’t like Linux computers. Supposedly it doesn’t like Vista or Windows 7 computers either (but what/who doesn’t, anyway?!?!). The problem is TCP window scaling, which (for performance reasons) tinkers with packets in a way that the router does not understand (possibly because the router is running firmware that is older than the concept of TCP window scaling, but firmware upgrades fail so I don’t know if the latest firmware fixes the problem). This command fixes the problem by turning off TCP window scaling.

echo 0 > /proc/sys/net/ipv4/tcp_window_scaling

Whew… Two years ago I bought two of the Acer budget or economy LCD screens from NewEgg (newegg.com). They’re the 2216 screens that are always nicely priced (mine are AL2216wbd but the last few letters change [my company has purchased several varieties including AL2216WBD and V223WBD -- all are great monitors for typical non-graphic-artist business use]). They worked fine in Windows XP with an ATI FireGL card.

Fast forward to today: I just built a new Linux machine running openSUSE 11.1. The NVidia driver install was simple using “the hard way” described here. But the screens gave me a headache within 30 seconds of looking at them. Text was pixilated and fuzzy, and just about everything was so bright that it had white outlines. It was hard to look at. I thought I installed the driver wrong and it was using the wrong resolution and color combination — but it turns out the settings needed a little tweaking. I tried a bazillion different things, and I even contemplated going back to Windows (OUCH). Finally, I went through the painstaking effort of fiddling with all of NVidia’s settings. I am happy to say that this works:

Step 1: Edit /etc/X11/xorg.conf to add the settings described here in the section that begins with “For nVidia drivers you may have to disable automatic detection of DPI to set it manually.” It says to add these two settings to the Section “Device” section of xorg.conf:

  Option   "UseEdidDpi" "false"
  Option   "DPI" "96 x 96"

Step 2: Use the NVidia X Server Settings applet (just click the Gecko / Application Launcher and type nv in the search box) to adjust the brightness, contrast, and gamma. Those settings are under X Screen 0 -> X Server Color Correction. The brightness, contrast, and gamma settings pictured below worked best for me — the headache has gone away!!!

Note: This was my first attempt at using openSUSE. On my second attempt, I no longer had this problem. My guess is that I installed the wrong version of something-or-other which caused this problem.

If you have openSUSE 11.1, like I do, then you have Ruby 1.8.7. I encountered an error when trying to run ruby script/console and ruby script/server for the first time in openSUSE. This pretty much killed everything — most of my plug-ins and models didn’t load.

The problem is that, in Ruby prior to 1.8.7 (perhaps much prior, I don’t know), the [] and/or first methods on String returned an array of characters. Now that has changed so that they return an Enumerable::Enumerator.

I added a hack to the top of /config/boot.rb so that it’d behave. I’ll figure out the real problem later — I’m busy! I found this example elsewhere, but I chose to but it in boot.rb:

unless '1.9'.respond_to?(:force_encoding)
  puts 'un-defining :chars method on String for ruby 1.8.7 compatibility'
  String.class_eval do
    begin
      remove_method :chars
    rescue NameError
      # OK
    end
  end
end

And unformatted:

Frequently, I need to look at my Rails app’s log file. Normally, I use tail -f production.log and hope it doesn’t scroll by so fast that I can’t read it. Sometimes, I need to watch the log file but can’t do so because it’s just too fast. Here’s a nifty Linux command to find what you’re looking for. It uses tail to follow the production log file, but only spits out lines that you are looking for. In my case, I just want to show the URLs of slow requests (e.g. any request that takes longer than one second). The command below looks for the “(0 reqs/sec)” lines in the log file but can easily be changed to look for other things. Just press CTRL+C to terminate it when you’re done.

tail -f production.log | while read line ; do echo "$line"| grep '(0 reqs/sec)' ; done

And on one line without formatting:

tail -f production.log | while read line ; do echo "$line"| grep '(0 reqs/sec)' ; done

Sometimes you run test queries against large databases, or you copy & paste a query but leave out the where clause, or otherwise make a mess. If you ever accidentally execute a query in MySQL that spikes the CPU, here’s how you kill or stop it:

show processlist;

That will return a list describing what’s going on in MySQL. Hopefully the result set is small enough that you can pinpoint your slow query. Look for a row with a large value for the Time column and something other than Sleep in the Command column. Look at the rest of the columns to be sure you’ve found what you’re looking for.

Once you’re sure you have the right one, use the kill command (note: this is the MySQL kill command for killing MySQL internal threads, not the OS-level command for killing processes!).

kill query 21445;

In Ruby on Rails, you can specify the order in which plug-ins will load.

In Rails 2.0, if you want to put a few plug-ins at the top of the order, and you didn’t really care about the rest, you can do so with this syntax:

config.plugins = [:my_first_plugin, :my_second_plugin, :all]

Prior to Rails 2.0, in Rails 1.2.3 for example, you have to specify every plug-in in order to take advantage of this feature because the :all option is not supported. This is a pain for those of us who have some Rails 2.0 apps and some pre-2.0 apps. Especially when we do a lot of plug-in work. Below is a workaround. It takes your array of preferred plug-ins and then appends the rest. That may or may not be what Rails 2.0 does with the :all symbol.

order = ['my_first_plugin', 'my_second_plugin']
others = Dir.new("#{RAILS_ROOT}/vendor/plugins").select{|f|File.directory?("#{RAILS_ROOT}/vendor/plugins/#{f}") && f[0].chr!='.'}.sort
config.plugins = (order << (others-order)).flatten

And without the line breaks: