I ditched my iPhone 3G for a Nexus One. For me the reason was an extremely easy one: seemless integration with Google. I love the way it handles syncing email, contacts, calendar, and voice mail. To be honest, I don’t really use the phone for much else. I tracked my usage of apps on the iPhone and found them mostly to be novelty apps.

But being a Linux geek at heart and a Capricorn, I do like to have complete control! So I embarked on rooting the Nexus One as soon as it OTA updated to Android 2.2 (Froyo). After reading numerous threads, blogs and posts, here is my way of distilling all that info down into four easy steps.

Remember: this is for the stock ROM FRF91. I cannot explain — as I don’t know — what will happen if you screwed around with your phone in the past. This happens to be a phone fresh from the factory that OTA updated to Android 2.2 as soon as I turned it on! YMMV.

Step 01: Unlock Bootloader

• Download fastboot for Linux here
• Turn off the Nexus One
• Connect your phone to your computer via a USB cable
• Power it on by holding down the trackball as you hit the power button

you should see a text screen with three skateboarding Androids

• Open a terminal on your Linux box

navigate to where fastboot is located

• Run ./fastboot-linux devices

you should see some output
if you did not see output, you need Step 02: Modify UDEV
repeat above steps until output is seen

• Run ./fastboot-linux oem unlock
• Use the Volume Up to select Yes to Unlock bootloader

Step 02: Modify UDEV
AFAIK, this only applies to Ubuntu systems.

• sudo vi /etc/udev/rules.d/51-android.rules
• add the following lines to this file

SUBSYSTEM=="usb", SYSFS{idVendor}=="18d1", MODE="0666"
SUBSYSTEM=="usb", SYSFS{idVendor}=="0bb4", MODE="0666"

• sudo chmod a+rx /etc/udev/rules.d/51-android.rules
• sudo services udev restart

Step 03: Flash a Recovery Image

• Download the lastest recovery image here
• Turn off Nexus One
• Power in to Fastboot mode

hold down trackball as you hit the power button
same as in Step 01: Unlock Bootloader

• Run ./fastboot-linux devices

make sure you see the device

• Run ./fastboot flash recovery recovery-RA-nexus-v1.7.0.1.img
• Test recovery mode

use the Volume Down-key to toggle Reboot
hit the power button
hold down the Volume Down-key as it reboots
navigate to RECOVERY with the Volume Down-key
press the power button to select

• If all goes well, you’ll see a nice recovery menu

Step 04: Install Rooted Image

• Download the rooted image from here
• While in Recovery mode, perform a nandroid backup of your system
• Return to main menu and select USB-MS toggle

This will mount the SD card onto your Linux system

• Copy over froyo-rooter-signed.zip to the SD card
• Unmount the SD card in Linux
• Press the trackball to disable USB-MS mode
• From the Recovery menu select Flash zip from sdcard

Within a few seconds you will have a rooted Nexus One w/Froyo Android 2.2

• Power down or reboot the phone

If all went according to plan, you should have a rooted Nexus One. A quick way to tell is by looking for a new app call “Superuser Permissions.”

Good luck!

I got this idea from Linux Journal. After you have watched a video online, run this script to save a local copy in the same place this script is run.

Some pre-reqs: I assume Firefox is your browser in both Linux and OS X, and I assume you have mplayer installed in Linux and VLC in OS X.

Here’s the Linux version:

#! /bin/bash

clear

echo "Video Saver Script Foo by geezer"
echo

PID=`ps xfa | grep firefox | awk '/firefox/ { print $1 }' | head -1`
VIDEO=`ls -lU /proc/$PID/fd | grep Flash | awk '{ print $10 }' | tail -1`
DELETED=`ls -lU /proc/$PID/fd | grep Flash | awk '{ print $11 }' | tail -1`

if [ "$VIDEO" == "" ]; then
     echo "No video found!"
     exit
fi

if [ "$DELETED" == "(deleted)" ]; then
     echo "Video is no longer in cache! Please replay."
     exit;
fi

if [ "$1" == "-d" ]; then
	echo $PID
	echo $VIDEO
fi

echo -n "Name your video file: "
read NAME

cp $VIDEO $NAME.flv

echo
echo -n "Do you want to play the video now?  "
read ANSWER

case $ANSWER in
	y | y)
		mplayer $NAME.flv &> /dev/null &
		echo;;
	N | n)
		exit;;
	    *)
		exit;;
esac

And here’s the OS X version:

#! /bin/bash
clear

echo "Video Saver Script Foo by geezer"
echo

PID=`ps xa | grep firefox | awk '/firefox/ { print $1 }' | head -1`
VIDEO=`lsof -p $PID | grep FlashTmp | awk '{ print $9 }' | tail -1`

if [ "$VIDEO" == "" ]; then
	echo "No video found!"
	exit
fi

if [ "$1" == "-d" ]; then
	echo $PID
	echo $VIDEO
fi

echo -n "Name your video file: "
read NAME

cp $VIDEO $NAME.flv

echo
echo -n "Do you want to play the video now?  "
read ANSWER

case $ANSWER in
	Y | y)
                if [ -f "/Applications/VLC.app/Contents/MacOS/VLC" ]; then
                   open -a VLC $NAME.flv &> /dev/null &
                else
                   echo "VLC is not found."
                   exit
                fi

		echo;;
	N | n)
		exit;;
	    *)
		exit;;

esac

Most Gumstix devices I’ve encounter (Basix and Verdex Pro) come with a built-in Web server known as Boa. If you’ve ever watch the Gumstix boot from a console, you’ll see an error about gethostbyname. Once the Gumstix is up and running, you’ll find no Web server active. And any attempt to issue an /etc/init.d/boa start only results in the same gethostbyname error.

Here’s a simple fix.

Go to the boa.conf file located in /etc/boa/ directory and find the line with ServerName. Simply change what’s there to a name of your choosing, like this example:

# ServerName: the name of this server that should be sent back to
# clients if different than that returned by gethostname + gethostbyname

ServerName www.mygumstix.net

Once the change is made, start the server with: /etc/init.d/boa start

If all goes well, navigate with your browser to the IP address of your Gumstix and you should see the default Gumstix web page!

I needed to implement a reliable network connection into my Verdex Pro once it was attached to the GPSstix since the USB networking is hosed. Here was my solution to this wireless networking issue.

Step 1. Enable only necessary options
As you’ll see from my config from /etc/default/bluetooth, I disable most Bluetooth options. The key parts are at the end dealing with PAND (Personal Area Network daemon).

# Bluetooth configuraton file

# Attach to the onboard bluetooth adapter  (allowed values are "true" and "false")
HCIATTACH_ENABLE=true

# Start of hcid (allowed values are "true" and "false")
HCID_ENABLE=false

# Config file for hcid
HCID_CONFIG="/etc/bluetooth/hcid.conf"

# Start sdpd (allowed values are "true" and "false")
SDPD_ENABLE=false

# Start hidd (allowed values are "true" and "false")
HIDD_ENABLE=false

# Arguments to hidd
#HIDD_OPTIONS=""

# Run hid2hci (allowed values are "true" and "false")
HID2HCI_ENABLE=false

# Bind rfcomm devices (allowed values are "true" and "false")
RFCOMM_ENABLE=false

# Config file for rfcomm
RFCOMM_CONFIG="/etc/bluetooth/rfcomm.conf"

# Start dund (allowed values are "true" and "false")
DUND_ENABLE=false

# Arguments to dund
DUND_OPTIONS="--listen --persist"

# Start pand (allowed values are "true" and "false")
PAND_ENABLE=true

# Arguments to pand
PAND_OPTIONS="--role GN --listen"

Step 2 Add the bnep0 interface
Assign your Gumstix a static IP address so you can connect. Here’s a snippet of my /etc/network/interfaces file.

iface bnep0 inet static
      address 10.10.10.1
      netmask 255.255.255.252
      network 10.10.10.0
      broadcast 10.10.10.3

The netmask above defines a two-host network. Your outside connection (laptop, desktop, mobile device) must use 10.10.10.2 as its IP address as well as the netmask above. Sure, I could have installed a small DHCP server to issue IPs automatically, but since the same device will connect to the Gumstix, I didn’t see the need.

Anyone wishing to use sox for audio file conversions on the Gumstix may be interested in this information.

While you could simply cross-compile sox using the OE environment for Gumstix, you’ll quickly learn that a number of additional dependencies are required. Here they are in the order they need to be installed (all in the OE environment):

• libogg0 >=1.1
• libvorbis >= 1.0.1
• libmad0 >= 0.15.16

I used sox-13.0.0 for my app. A few flags have changed between the various versions, but here is what I used to convert a directory full of .raw audio files to .wav files:

for i in /media/card/*.raw
do
    sox -2 -s -r 8000 -c2 $i ${i%.*}.wav
done

The flags indicate the following:

-2 sample size in bytes
-s signed-integer
-r 8000 is the sample rate
-c2 is the number of channels

Good luck! Hope it helps.

For anyone new to Python, here’s a simple script to help copy files of a particular extension type to another location.

My scenario was to copy a bunch of ISO images from my Linux box to my MacBook. Sure I could have mounted the Linux box, selected all the files and do the simple drag-and-drop to my DVD library. As I did that, I noticed ALL the files were being copied at the same time. This was causing way too much “back and forth” of the drive head on the server as it attempted to copy various bits and bytes of each file.

I wanted a way to copy each ISO, one at a time, without me having to wait for each copy to complete to begin the next ISO. This sounds like a job for a script! So here’s the Python script I put together to accomplish the task. At least the drive head on the server wasn’t getting thrashed! And now I could continue doing other tasks.

import os
import fnmatch

for movie in os.listdir('/Volumes/sda1'):
	if fnmatch.fnmatch(movie, '*.ISO'):
		print movie
		os.system("cp /Volumes/sda1/%s ." % movie)

Substitute *.ISO with your own file extension. You can also put in any valid UNIX command in the os.system() function to do your bidding.

More details on these Python modules can be found here:

os module
fnmatch module

The Problem

I’ve come to notice a quirk in the USB networking capabilities between my basix Gumstix mobo and my Ubuntu laptop. And I’m not the only one who has noticed this quirk. It has also appeared to manifest iteself on the connex boards as well. Maybe we’re not doing something right. But we simply want to have USB networking up and running at boot while a USB cable remains connected between the Gumstix and the laptop. Sure, we could simply pull the USB cable out and reinsert then all is fine. But shoud we really have to do this?

The Solution

The solution is to run /etc/init.d/networking force-reload once the system is finally up and running. Here’s how I implemented it for automation:

Step 1) Modify /etc/network/interfaces to contain the following (use your own IP addresses):

auto usb0
iface usb0 inet static
     address x.x.x.x
     netmask x.x.x.x
     network x.x.x.x
     pre-up /sbin/modprobe g_ether
     post-down /sbin/rmmod g_ether

Step 2) Add the following to /etc/rc.local:

/etc/init.d/networking force-reload

Note: Make sure rc.local is executable!

Step 3) Add a symlink in /etc/rc5.d to point to /etc/rc.local:

ln -s /etc/rc.local /etc/rc5.d/S95ReloadUSB

That should solve it even if you power your Gumstix over USB. If anyone can explain why we don’t need this workaround, I would be very interested in hearing what you have to say.

The following are instructions on how I was able to get audio working on the Gumstix basix mobo with a 400MHz PXA255 and Bluetooth. It runs the most recent version of Gumstix OpenEmbedded.

A few assumptions about your skills:

1. You can log into the Gumstix (either SSH or console)
2. You can gain access to the Internet from the Gumstix (either via Bluetooth or bridging usb0 to eth0)
3. You have a sound source (mic) and speakers or headphones

Log into your Gumstix. We need a tool that will allow us to record and play audio. Assuming you have that Internet connection, then from the Gumstix command line:

ipkg install alsa-utils-aplay

Next we need to configure the ALSA mixer for sound. From the command line:

alsamixer

An ncurses GUI pops up. Configure as follows:

1. Press the TAB key until [ALL] is highlighted at the top left in the row labeled “View:”
2. Use the up arrow to increase the Master Volume to a desired level (I set it at 76)
3. Press the “M” key (mute) to unmute the Master Volume
4. Use the right arrow to highlight “Capture”
5. Use the up arrow to set the capture volume (I use 73)
6. Press ESC to exit the ALSA mixer

Let’s save these mixer settings so we don’t have to configure the ALSA mixer every time the Gumstix boots:

alsactl store

Now issue the following commands to list your CAPTURE and PLAYBACK devices:

arecord -l
aplay -l

You should get some output along the lines of:

**** List of CAPTURE Hardware Devices ****
card 0: Gumstix [Gumstix], device 0: UCB1400 AC97 HiFi-AC97-0 []
Subdevice: 1/1
Subdevice #0: subdevice #0

And almost the same output with aplay, but CAPTURE is replaced with PLAYBACK.

Now let’s record something. You will have many choices and control over the quality of your recording. However, for our test we will record with some standard settings. Run the following on the command line:

arecord -d 5 -f cd test.wav

This says, “record for a duration of five seconds in CD quality (44100 HZ & stereo) then save it to test.wav”. NOTE: Failure to save this simple test to an external storage medium will fill up your root file system!

To hear what you recorded, simply type:

aplay test.wav

Congratulations! I hope you were successful in getting your audio recorded and played back.

The sample file above weighs in (for me) at 861.4k. If size is a concern, you can drop the stereo to mono and reduce the bit rate. Here’s one last example to illustrate the space savings at the expense of perfect stereo sound:

arecord -c 1 -d 5 -f S16_LE test.wav

This says, “record only one channel for five seconds in a signed 16-bit little endian format then save it to test.wav”. The result will be an audio file recorded in mono at 8000 HZ. Now my file only weights in at 78.2k vs. 861.4k. Wow! However, you will surely notice a difference in quality.

Now go do good things!

The other day I found myself working on an installation script for a program that required a number of software packages from Ubuntu’s repositories.

After a couple hours of continually hitting the “y” button during testing, I finally figured out a method to automate the process without user interaction. You use a “-y” flag with apt-get (it pays to read the man pages!).

So if you’re looking for an automated way to download and install packages from within a Bash script, feel free to use this function I whipped up. Of course, if you have ways to improve it, please post some comments!

Be sure to add the packages you need to the script! Those are the one’s I needed. I’m sure your needs are different.

Enjoy!

#/bin/bash

functionInstall ()
{
     clear
     packages=(build-essential libpcap-dev bison flex libgtk2.0-dev)
     echo "Downloading and installing packages."
     echo
     for i in "${packages[@]}"; do
          echo "     * $i... "
          /usr/bin/apt-get -y install $i &> /dev/null
          echo "done."
     exit 0
}

In my previous post I mentioned the three talks which I found the most informative and useful. I’ve posted the talks’ associated presentations and whitepapers in the Reference Material section for your downloading pleasure. I hope you enjoy these as much as I did.