John Stanfield dot com

I have a lot of Rails apps (1.x, 2.x, and 3.x) and keeping Ruby versions and gem updates correct is difficult. RVM to the rescue. It worked a few days ago (right after installation) but now I keep getting the “RVM is not a function” message, and I’ve tried all of the suggestions at rvm.io. At the moment I’m in too big of a hurry to figure this out, but I tried the solution below and it worked.

If you get the message

RVM is not a function, selecting rubies with ‘rvm use …’ will not work.
You need to change your terminal emulator preferences to allow login shell.
Sometimes it is required to use `/bin/bash –login` as the command.

Please visit https://rvm.io/integration/gnome-terminal/ for a example.

Try this: if you have SSH turned on

ssh your-user-name@localhost
rvm use 1.8.7

I needed to fix an older app today that was written with Rails 1.2.3. It wasn’t sending inline attachments in emails correctly. It was trying to use one of the many gems named something like inline attachment (which may not be suitable for use with older Rails versions), but gave up and did it manually. I decided that it was easier to hand-code the ActionMailer::Part parts of the email than to use a gem designed to make this easier. I think that the app broke when the correct gem was uninstalled and could not be reinstalled (because it was removed from wherever it was published).

class Mailer < ActionMailer::Base
  def postcard
    recipients 'you@yourdomain'
    from       'me@mydomain.com'
    subject    'my email to you'

    image_path = "#{RAILS_ROOT}/public/images/something.jpg"
    base = File.basename(image_path)
    cid = "#{base}@mydomain.com"

    part :content_type => 'multipart/related' do |pt|
       pt.part :content_type=> 'text/html' do |html|
         html.body = "<img src=\"cid:#{cid}\" />"
       end
       attachment :content_type => "image/jpg; name=#{base}" do |a|
         a.headers["Content-ID"]="<#{cid}>"
         a.body = File.read(image_path)
       end
    end
  end
end

There might already be a way to do this, but I could not figure it out. This morning I needed to take an image, resize it four times, and copy it into the eight Android drawable folders (drawable-hdpi, drawable-hdpi-v5, drawable-ldpi, drawable-ldpi-v5, drawable-mdpi, drawable-mdpi-v5, drawable-xhdpi, and drawable-xhdpi-v5). Rather than do that manually, I resized it once for the largest density (xhdpi) and wrote a script to do the rest. This script:

• assumes that the target image is the correct size for xhdpi
• resizes it for the lower densities
• copies the resized image into the drawable folder.

I wanted to name it resize as in resource-ize but that looks like resize as in change-the-size. So I instead named the script rezize. Now I just save the file in the res folder (my_file.png), rezize my_file.png, and then delete the file. It could be more elegant, but this is good enough for me.

#!/bin/bash
# arg 1 is file name
#   - will use identify to get height and width
#   - will assume that the file is the correct dimensions for xhdpi
#   - will do 75% for hdpi
#   - will do 50% for mdpi
#   - will do 37.5% for ldpi

WIDTH=$(identify -format "%w" "$1")
HEIGHT=$(identify -format "%h" "$1")

echo copying $1 to drawable-xhdpi/$1 and leaving size as ${WIDTH}x${HEIGHT}
echo copying $1 to drawable-xhdpi-v5/$5 and leaving size as ${WIDTH}x${HEIGHT}
cp "$1" "drawable-xhdpi/$1"
cp "$1" "drawable-xhdpi-v5/$1"

newwidth=$(echo "$WIDTH*0.75" | bc)
newheight=$(echo "$HEIGHT*0.75" | bc)
echo copying $1 to drawable-hdpi/$5 and making size ${newwidth}x${newheight}
echo copying $1 to drawable-hdpi-v5/$5 and making size ${newwidth}x${newheight}
convert -resize ${newwidth}x${newheight} "$1" "$1.resized"
cp "$1.resized" "drawable-hdpi/$1"
mv "$1.resized" "drawable-hdpi-v5/$1"

newwidth=$(echo "$WIDTH*0.5" | bc)
newheight=$(echo "$HEIGHT*0.5" | bc)
echo copying $1 to drawable-mdpi/$5 and making size ${newwidth}x${newheight}
echo copying $1 to drawable-mdpi-v5/$5 and making size ${newwidth}x${newheight}
convert -resize ${newwidth}x${newheight} "$1" "$1.resized"
cp "$1.resized" "drawable-mdpi/$1"
mv "$1.resized" "drawable-mdpi-v5/$1"

newwidth=$(echo "$WIDTH*0.375" | bc)
newheight=$(echo "$HEIGHT*0.375" | bc)
echo copying $1 to drawable-ldpi/$5 and making size ${newwidth}x${newheight}
echo copying $1 to drawable-ldpi-v5/$5 and making size ${newwidth}x${newheight}
convert -resize ${newwidth}x${newheight} "$1" "$1.resized"
cp "$1.resized" "drawable-ldpi/$1"
mv "$1.resized" "drawable-ldpi-v5/$1"

I had a heck of a time getting my development machine to recognize my Droid 2. I could plug in the USB cable, see the drive mounted, and everything seemed to work. But Eclipse would not see it when I tried to run an Android application. Executing adb devices (located in ~/android-sdks/platform-tools) showed that the device had no permissions.

Google created a Using Hardware Devices guide to help get it working, but it doesn’t work as-is — probably because there are so many flavors and releases of Linux.

Google also created a list of vendor IDs which, although helpful, didn’t work because, at least on my machine, the ‘B’ in 22B8 needs to be in lower case.

Below are the steps I went through to get it to work:

First try (no changes were made)

cd ~/android-sdks/platform-tools
./adb devices
List of devices attached
???????????? no permissions

Second try (copying the example in step 3a here and the Motorola code here)
/etc/udev/rules.d/51-android.rules
SUBSYSTEM==”usb”, ATTR{idVendor}==”22B8″, MODE=”0666″, GROUP=”plugdev”

sudo udevadm control –reload
(unplug and plug device)
cd ~/android-sdks/platform-tools
./adb devices
List of devices attached
???????????? no permissions

Third try (removing the GROUP attribute)
/etc/udev/rules.d/51-android.rules
SUBSYSTEM==”usb”, ATTR{idVendor}==”22B8″, MODE=”0666″

sudo udevadm control –reload
(unplug and plug device)
cd ~/android-sdks/platform-tools
./adb devices
List of devices attached
???????????? no permissions

Fourth try (lower-casing the ATTR{idVendor} attribute) — BINGO!
/etc/udev/rules.d/51-android.rules
SUBSYSTEM==”usb”, ATTR{idVendor}==”22b8″, MODE=”0666″

sudo udevadm control –reload
(unplug and plug device)
cd ~/android-sdks/platform-tools
./adb devices
List of devices attached
C70C81FB96E295FE no permissions

Note 1: That’s a made-up device ID. I copied 16 random hex characters from here.
Note 2: Word Press is a PITA and replaces double-dashes with m-dashes. The command to restart udev is udevadm control double-dash-reload
Note 3: I did this on openSUSE 11.4. I have also done it on 12.1 but need to confirm the rule is the same on that other machine.