Category Archives: Raspberry Pi

Why did I switch back to Raspbian on my RPi server?

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Frankly, while I’m super happy user of Ubuntu on desktop and servers, I’ve been quite unsatisfied with Ubuntu for Raspberry Pi. Mostly, cause it ruined a few of my SD cards. I’ve realised that writing file access info to the card was one of the key factor here. Unfortunately, Ubuntu for RPi won’t but with noatime… while latest Rasbian has it by defualt.

What I like a lot about Raspbian Stretch Lite, is that beside natively supporting all Raspberry Pi features, it’s also cross platform compatible – it works super well on both, RPi2 and RPi3.

And yes, this blog among few other things is server from RPi2 🙂

Mount USB drive in RPi2

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By default, RPi2 limits power supply of USB ports to 0.6A, while most USB drives require more than that. This is why most USB drives cannot be used with RPi2 without external power supply to RPi2. Luckily, given that you have decent power supply (ie I have 2A charger), you can increase USB port max current, by editing `/boot/config.txt`.

IMPORTANT!!! RPi2 allows max 1.2A current through all 4 USB ports combined, so don’t even think about plugging two USB drives!!! This is because the maximum power allowed into the RPi2 is limited to 2A by the fuse (F1) so if one of your USB device draw 1A, then that leaves 1A for the RPi + GPIO + remaining USB devices.

First, check if your drive can be detected without tweaking

sudo blkid

If you see only mmcblk0 entries, this means that your drive is not recognised. 

/dev/mmcblk0p1: ...
/dev/mmcblk0p2: ...
/dev/mmcblk0: PTUUID="d2fd971c" PTTYPE="dos"

Add max_usb_current=1 to /boot/config.txt:

Reboot and check if your USB drive is visible after restart: 

sudo reboot
sudo blkid

Now, you should see new entry: 

/dev/mmcblk0p1: ...
/dev/mmcblk0p2: ...
/dev/mmcblk0: PTUUID="d2fd971c" PTTYPE="dos"
/dev/sda1: LABEL="turo"...

And you should be able to mount it:

sudo mkdir -p /media/turo
sudo mount /dev/sda1 /media/turo

Inspired by www.htpcguides.com and www.raspberrypi.org/forums.

Raspberry Pi2 with Ubuntu Sever and Drupal?

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I decided to celebrate 25th B-day of Linux by putting the latest Ubuntu 16.04 on my Raspberry Pi 2 and setting up a webserver.
This is how I did it:

  1. First, get Ubuntu armf image and prepare memory card
    2. # get image
wget http://cdimage.ubuntu.com/ubuntu/releases/16.04/release/ubuntu-16.04-preinstalled-server-armhf+raspi2.img.xz

# make sure your SD card is on sdb ie by df -h
xzcat ubuntu-16.04-preinstalled-server-armhf+raspi2.img.xz | sudo dd of=/dev/sdb
  2. Configure new user & setup Drupal8 webserver
    3. # create new user & change hostname
sudo adduser USERNAME && sudo usermod -a -G sudo USERNAME
# edit /etc/hostname and add `127.0.1.1 newHostname` to /etc/hosts
sudo reboot

# generate locales
sudo locale-gen en_US.UTF-8
sudo dpkg-reconfigure locales

# install software
sudo apt install htop apache2 mysql-server libapache2-mod-php php-mysql php-sqlite3 php-curl php-xml php-gd git sqlite3 emacs-nox

My first impressions?
sudo apt is veeery slow. At first, I thought it’s due to old SD card I’ve been using, but it’s also true for newer SD card.
Some packages are missing (ie. git-lfs), but you can get them using some workarounds.

But everything just works!
You can check the mirror of https://ngschool.eu/ running on RPi2 here.
Maybe it’s not speed devil, but it stable and uses almost no energy 🙂

Cheers!

Inspired by Ubuntu’s Insights.

Installation of git-lfs on Ubuntu RPi2 (armf)

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Unfortunately, the standard way to install git-lfs doesn’t work on RPi2. But there is simple workaround: 

# install go
sudo apt-get install golang
# you may want to grab a coffee at this stage... ;) 

# get git-lfs from github
sudo -i
mkdir /root/gocode
export GOPATH=/root/gocode
go get github.com/github/git-lfs
cp gocode/bin/git-lfs /usr/bin

Testing connection speed between two computers

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I’ve expanded my home network with new switch and I wanted to test the connection speed between different computers. At first, I ran rsync, but I’ve quickly realised it’s limited by source/destination read/write speeds.
I found better way of measuring connection speed using netcat: 

# start listening on one computer ie 10.0.0.5
nc -vvlnp 12345 < /dev/null

# start broadcasting ~100MB from another computer
dd if=/dev/zero bs=1M count=100 | nc -vvn 10.0.0.5 12345
## 104857600 bytes (105 MB) copied, 8.89602 s, 11.8 MB/s

You can use more sophisticated tools for the same purpose ie. iperf:

# install on both boxes
sudo apt-get install iperf

# start server in one computer
iperf -s

# measure connection speed from client(s)
iperf -c server_IP
##[  5]  0.0-10.0 sec   112 MBytes  94.1 Mbits/sec

Inspired by AskUbuntu.

Sending emails from command-line using Gmail & SSMTP

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I wanted to send email reports from my computers. For that, the easiest is to create additional Gmail account (so your private email is safe) and set-up SSMTP:

sudo apt-get install ssmtp mailutils

Configure SSMTP: comment all lines in /etc/ssmtp/ssmtp.conf and add at the end (replacing HOSTNAME/USER/PASSWORD with your info):

root=postmaster
hostname=HOSTNAME
mailhub=smtp.gmail.com:465
AuthUser=USER@gmail.com
AuthPass=PASSWORD
FromLineOverride=YES
UseTLS=YES

Then, allow access from less secure apps to created Gmail account and enable one-time sign-in for new app without captcha. It’s strongly recommended not to use your private account for that purpose!

And send emails:

echo "email body" | mail -s "Test email from "`hostname` SOMEUSER@gmail.com

Voilà!

Note, this works perfectly fine in Ubuntu, as well as in Raspberry Pi.

NX server on Raspberry Pi

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Finally I had some time to get my hand on new Raspberry Pi 2.
I think it’s useful to access the RPi2 by ssh (work out of the box) and NX. Installation of NX server is quite time-consuming, but I think it’s worth to give it a try! Here is what I did: 

# install dependencies
sudo apt-get install xutils-dev expect xorg-dev libjpeg8-dev libpng12-dev cups xfonts-base x11-xserver-utils autoconf

sudo mkdir -p /usr/NX/{bin,etc}

# install freenx
wget http://pkgs.fedoraproject.org/repo/pkgs/freenx-server/freenx-server-0.7.3.tar.gz/856f597e139018f7ed62713c9d6c9ed5/freenx-server-0.7.3.tar.gz
tar xpfvz freenx-server-0.7.3.tar.gz
cd freenx-server-0.7.3
patch < gentoo-nomachine.diff
make
sudo make install

# copy node.conf
# and replace #COMMAND_MD5SUM="openssl md5" with COMMAND_MD5SUM="md5sum"
# and #COMMAND_START_GNOME=gnome-session with COMMAND_START_GNOME="/usr/bin/startlxde"
sudo cp node.conf.sample /usr/NX/etc/node.conf

# get nx source
wget http://code.x2go.org/releases/source/nx-libs/nx-libs_3.5.0.13-full.tar.gz
tar xpfvz nx-libs_3.5.0.13-full.tar.gz
cd nx-libs_3.5.0.13

# compile & relax for ~1 hour...
make build-full
sudo make install

# copy libs and binaries
sudo ln -s /usr/lib/NX3/lib/nx /usr/NX/lib
sudo cp -a nx-X11/lib/X11/libNX_X11.so* nx-X11/lib/Xext/libNX_Xext.so* nx-X11/lib/Xrender/libNX_Xrender.so* nxcomp/libXcomp.so* nxcompext/libXcompext.so* nxcompshad/libXcompshad.so* /usr/NX/lib
sudo cp -a nx-X11/programs/nxauth/nxauth nx-X11/programs/Xserver/nxagent nxproxy/nxproxy /usr/NX/bin

# link binaries & install
for f in /usr/bin/nx*; do echo $f; sudo ln -s $f /usr/NX/bin; done
sudo nxsetup --install

After these steps, you should be able to connect with NX client using fake GNOME session.
Raspberry Pi 2 over NX

Post is based on TiaoWiki with some updates/improvements.