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How to Disable Graphics Mode on Raspberry Pi

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set default systemd target

One thing you definitely need to do on your Raspberry Pi is decide if it's going to be used as desktop. And if not, disable the graphics mode. What this will do is save you a sizeable percentage of available memory by not starting Xorg and iniitalise your graphics desktop environment

Use systemd To Confirm Current Boot Mode

Simply run the systemctl command with get-default option:

greys@becky:~ $ systemctl get-default
graphical.target

graphical.target is the name of systemd target – a group of systemd services forming a defined system state. graphical.target means a combination of systemd services that will start graphics mode and graphics desktop environment.

Change systemd Target to Console Mode in Raspbian

We'll use the set-default option of systemctl like this:

greys@becky:~ $ sudo systemctl set-default multi-user.target

and then run get-default again to confirm the new default systemd target:

greys@becky:~ $ systemctl get-default
multi-user.target

That's it! Reboot your Raspberry Pi now and it won't start graphics mode.

Have fun!

See Also

Removed DHCP Daemons in Raspbian

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Raspberry Pi 4

I got one of my Raspberry Pi servers attempting to obtain DHCP IP address, a behavior that ignored my static IP address configuration.

Not sure why, but it appeared I'd be getting an extra DHCP address, from the same network segment, in addition to the static IP the Raspberry Pi already had.

Normally I'd just disable the service, but since my home office network is fairly static, I figured I would just remove the DHCP package.

WARNING: do not follow my steps unless you're in the same situation and pretty sure you're using static IP addressing.

Double Check that You're Using Static IP

Check your /etc/network/interfaces file, it should have something similar for your primary interface – in wired network cable case it's eth0:

auto eth0
iface eth0 inet static
    address 192.168.1.99
    netmask 255.255.255.0
    gateway 192.168.1.1

Also, run ip a and make sure you're seeing this same IP among the active interfaces:

greys@s7:~ $ ip a
1: lo:  mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0:  mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether b8:27:ee:66:88:ff brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.99/24 brd 192.168.1.255 scope global eth0
       valid_lft forever preferred_lft forever

Remove ISC DHCP Client

So I did this:

root@srv:~# apt-get remove isc-dhcp-client
 Reading package lists… Done
 Building dependency tree
 Reading state information… Done
 The following packages were automatically installed and are no longer required:
   libdns-export1104 libisc-export1100
 Use 'apt autoremove' to remove them.
 The following additional packages will be installed:
   dhcpcd5
 Suggested packages:
   dhcpcd-gtk
 The following packages will be REMOVED:
   isc-dhcp-client
 The following NEW packages will be installed:
   dhcpcd5
 0 upgraded, 1 newly installed, 1 to remove and 207 not upgraded.

All cool? Not really. If you read carefully, you'll notice that I removed isc-dhcp-client, but automatically installed dhcpcd5 – which started making DHCP requests again.

Remove DHCPcD5

Next step then! Let's remove DHCPcD5:

root@srv:~# apt-get remove dhcpcd5
 Reading package lists… Done
 Building dependency tree
 Reading state information… Done
 The following additional packages will be installed:
   isc-dhcp-client
 Suggested packages:
   avahi-autoipd isc-dhcp-client-ddns
 The following packages will be REMOVED:
   dhcpcd5
 The following NEW packages will be installed:
   isc-dhcp-client
 0 upgraded, 1 newly installed, 1 to remove and 207 not upgraded.

Much better!

Or is it? If you look closer, you'll see that this command installed isc-dhcp-client back.

Delete both DHCP Client Packages

This time I specified both packages to be removed. I even used apt-get purge instead of apt-get remove – to definitely destroy any configs:

root@srv:~# apt-get purge dhcpcd5 isc-dhcp-client
 Reading package lists… Done
 Building dependency tree
 Reading state information… Done
 The following packages were automatically installed and are no longer required:
   libdns-export1104 libisc-export1100
 Use 'apt autoremove' to remove them.
 The following additional packages will be installed:
   pump
 The following packages will be REMOVED:
   dhcpcd5* isc-dhcp-client*
 The following NEW packages will be installed:
   pump
 0 upgraded, 1 newly installed, 2 to remove and 207 not upgraded.

When this installed pump (that's apparently another BOOTP/DHCP client – I never even heard about it before), I got curious.

Having researched online, it appears one can configure static IP in Raspberry Pi using DHCP client configs. Doesn't sound right to me! There's also the systemd way to disable dhcpd.service, but at this stage I was not looking for half measures.

Having carefully considered this, I decided to unstall the whole lot. It also removed wicd* (Wired and Wireless Network Connection Manager) bunch which is another set of packages for managing network interfaces and connections.

I'm honestly suprised and seriously suprised how involved a network interface and IP address configuration is! Since I'm not using any of these niceties and because this is a static server-like environment where I'm not switching Wi-Fi networks or changing connection profiles all the time, I'm comfortable letting it all go.

Uninstalling DHPCP clients, pump and Wicd

WARNING: be super sure you're using static IP addressing on your Raspberry Pi system before running the next command.

Here's the final uninstall command:

root@s7:~# apt-get remove dhcpcd5 isc-dhcp-client pump
Reading package lists… Done
Building dependency tree
Reading state information… Done
Package 'isc-dhcp-client' is not installed, so not removed
Package 'pump' is not installed, so not removed
The following packages were automatically installed and are no longer required:
  libdns-export1104 libisc-export1100 openresolv python-wicd
Use 'apt autoremove' to remove them.
The following packages will be REMOVED:
  dhcpcd5 wicd wicd-daemon wicd-gtk
0 upgraded, 0 newly installed, 4 to remove and 207 not upgraded.

FINALLY! No more DHCP requests from this server 🙂

pS: on a somewhat relevant note, think I'll upgrade all them 207 packages – but first will complete a reboot to check network configuration still works for the static IP.

See Also

Upgrading Raspbian OS from Stretch to Buster

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With recently released Debian 10 Buster it's possible to upgrade Raspbian OS on your Raspberry Pi device to the same release.
Raspberry Pi 4

Debian 10 Buster got released a while back and this means it should be possible to upgrade Raspbian OS on Rasberry Pi devices to the Raspbian Buster as well. Raspbian OS is based on Debian as you remember.

Step 1: Confirm Your Current Linux Kernel and OS release

Always a good step: confirm Raspbian version and check your current Linux Kernel version:

greys@s7:~ $ uname -a
 Linux s7 4.19.42-v7+ #1219 SMP Tue May 14 21:20:58 BST 2019 armv7l GNU/Linux
 greys@s7:~ $ cat /etc/debian_version
 9.9

Step 2: Update Existing Release Before Upgrading to the Next

Just like in the upgrade Jessie to Stretch procedure, we start with using apt-get command to upgrade existing packages available for the current release.

The reason it's recommended to do this is by moving to the latest available version in your current release you are minimising the changes required for the upgrade to the next release. Changes and configuration file syntax are not likely to be as dramatic between last version in current release and first version in the next release.

We refresh list of available updates:

greys@s7:~ $ sudo apt-get update

and install these updates:

 greys@s7:~ $ sudo apt-get upgrade
 Reading package lists… Done
 Building dependency tree
 Reading state information… Done
 Calculating upgrade… Done
 The following packages will be upgraded:
   cups-browsed cups-filters cups-filters-core-drivers dbus dbus-x11 fonts-opensymbol libcupsfilters1 libdbus-1-3 libexpat1 libexpat1-dev
   libfontembed1 libraspberrypi-bin libraspberrypi-dev libraspberrypi-doc libraspberrypi0 libreoffice libreoffice-avmedia-backend-gstreamer
   libreoffice-base libreoffice-base-core libreoffice-base-drivers libreoffice-calc libreoffice-common libreoffice-core libreoffice-draw
   libreoffice-gtk libreoffice-gtk2 libreoffice-impress libreoffice-java-common libreoffice-librelogo libreoffice-math libreoffice-nlpsolver
   libreoffice-ogltrans libreoffice-pdfimport libreoffice-report-builder libreoffice-report-builder-bin libreoffice-script-provider-bsh
   libreoffice-script-provider-js libreoffice-script-provider-python libreoffice-sdbc-hsqldb libreoffice-sdbc-postgresql libreoffice-style-galaxy
   libreoffice-style-tango libreoffice-systray libreoffice-wiki-publisher libreoffice-writer libssl-dev libssl-doc libssl1.0.2 libssl1.1 libzmq5
   nodered omxplayer openssl patch python3-uno raspberrypi-bootloader raspberrypi-kernel rpi-chromium-mods uno-libs3 ure vim vim-common vim-runtime
   vim-tiny xxd
 65 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
 Need to get 176 MB of archives.
 After this operation, 9,103 kB of additional disk space will be used.
 Do you want to continue? [Y/n] y
...

Run apt-get dist-upgrade too, in my case it shows zero packages:

greys@s7:~ $ sudo apt-get dist-upgrade
 Reading package lists… Done
 Building dependency tree
 Reading state information… Done
 Calculating upgrade… Done
 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

Step 3: Upgrade Raspbian OS to Buster

Three elements to this step:

  1. Update release code name in /etc/apt/sources.list
  2. Download list of available package updates
  3. Upgrade Raspbian OS

Update release name in /etc/apt/sources.list

First, let's edit /etc/apt/sources.list file:

greys@s7:~ $ sudo vi /etc/apt/sources.list

I changed this:

to this:

Refresh packages info with apt-get update

Now we can refresh information about available package updates:

greys@s7:~ $ sudo apt-get update

And, finally, we're ready to…

Upgrade Raspbian packages to Buster release

greys@s7:~ $ sudo apt-get upgrade
Reading package lists… Done
Building dependency tree
Reading state information… Done
Calculating upgrade… Done
...

… and finish it off with apt dist-upgrade:

greys@s7:~ $ sudo apt-get dist-upgrade
 Reading package lists… Done
 Building dependency tree
 Reading state information… Done
 Calculating upgrade… Done
 The following packages were automatically installed and are no longer required:
   ...
The following packages will be REMOVED:
   gnome-themes-standard-data gstreamer1.0-omx gstreamer1.0-omx-rpi gstreamer1.0-omx-rpi-config idle-python3.5 libcupscgi1 libcupsmime1 libcupsppdc1
   libcurl3 libgles1-mesa libllvm3.9 libmariadbclient18 libreoffice-gtk libreoffice-style-galaxy libreoffice-systray libsensors4 libservlet2.5-java
   libtirpc1 netsurf-gtk python3-spidev raspi-copies-and-fills xserver-xorg-video-fbturbo
 The following NEW packages will be installed:
...
 533 upgraded, 459 newly installed, 22 to remove and 0 not upgraded.
 Need to get 861 MB/862 MB of archives.
 After this operation, 1,045 MB of additional disk space will be used.
 Do you want to continue? [Y/n]

Step 4: Confirm Successful Upgrade

We need to reboot the Raspberry Pi now:

greys@s7:~ $ sudo shutdown -r now

…and run uname -a command and inspect the /etc/debian_version file to confirm that our Raspberry Pi is indeed running the latest version of Raspbian OS now:

See Also

Ordered Raspberry Pi 4!

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Screen Shot 2019-06-24 at 23.54.13

Apologies for a bunch of Raspberry Pi 4 posts in a row – I was both excited about Raspberry Pi 4 platform and away from my home lab (while enjoying summer holidays in Turkey). This is probably the last update on this for the next couple of weeks.

I Finally Ordered Raspberry Pi 4 with 4GB RAM

Got the email from The Pi Hut that Raspberry Pi 4 with 4GB RAM is back in stock and ordered it immediately. Am lookiing forward to setting it up, especially in the light of news that many opportunities open up – like Kali Linux available for Raspberry now.

Raspberry Pi Beginner's Guide

I also got the beginner's guide book delivered yesterday – will be great to catch up on the recent developments of both hardware and software platform. I also am a strong believer in (re)organizing knowledge – so even with my 20+ years of Unix/Linux experience I still enjoy reading technical books of all levels: even a beginner level book may be useful to properly (re)learn and memorize basics of a hardware platform or software solution. One useful/interesting idea about a book is all you need to make it worth the money spent.

That's it for today! Will be catching up on news and publishing more shortly.

See Also

4GB Raspberry Pi 4 Model is Out of Stock

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raspberry-pi4-specs
Raspberry Pi 4

Wow, demand for the latest and greatest Raspberry Pi 4 is bigger than I thought! I didn't want to order it right when Raspberry Pi 4 was announced, and will have to wait a few weeks now until all the pre-orders are fulfilled.

Why Raspberry Pi 4 Model with 4GB is Most Popular

I belive Raspberry Pi 4 with 4GB RAM is the closest yet to a fully functional desktop system: you can develop software, test and host websites, setup your own cloud systems and even play games like Minecraft with the smoothest experience.

I also think Raspberry Pi 4 is still pretty cheap, so the extra eur10-20 you will pay to get more powerful model is well worth the relatively dramatic gains from such an upgrade.

Finally, dual monitor setup with 4K resolutions is another very tempting feature of the Raspberry Pi 4 – and while it's available on all the latest models, I think the 4GB version is most popular because users plan to run more applications and more advanced software development setups with extra memory available.

ModMyPi, the vendor I used to get everything Raspberry Pi from, has just been purchased by ThePiHut company – and their website shows Raspberry Pi 4 with 4GB out of stock. Hope this is not for long as I really want to get the latest model for some experiements in my Unix Tutorial Hardware Lab.

See Also

Unix Fun: cowsay command

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Screen Shot 2019-06-10 at 12.16.32.png

cowsay is a comman line tool that you can install on any Linux or Unix distro to render funny text updates as if they're told by a cute text mode cow. There are lots of options to customise the look of both the cow and the text message.

Installing cowsay in Raspbian OS

I decided to install cowsay on one of my Raspberry Pi systems at home:

greys@becky:~ $ sudo apt install cowsay
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
lxkeymap python-cairo python-gtk2 python-xklavier
Use 'sudo apt autoremove' to remove them.
The following additional packages will be installed:
cowsay-off
Suggested packages:
filters
The following NEW packages will be installed:
cowsay cowsay-off
0 upgraded, 2 newly installed, 0 to remove and 182 not upgraded.
Need to get 27.9 kB of archives.
After this operation, 114 kB of additional disk space will be used.
Do you want to continue? [Y/n] y
Get:1 http://ftp.heanet.ie/mirrors/raspbian/raspbian stretch/main armhf cowsay all 3.03+dfsg2-3 [20.1 kB]
Get:2 http://ftp.heanet.ie/mirrors/raspbian/raspbian stretch/main armhf cowsay-off all 3.03+dfsg2-3 [7,816 B]
Fetched 27.9 kB in 0s (60.1 kB/s)
Selecting previously unselected package cowsay.
(Reading database ... 211819 files and directories currently installed.)
Preparing to unpack .../cowsay_3.03+dfsg2-3_all.deb ...
Unpacking cowsay (3.03+dfsg2-3) ...
Selecting previously unselected package cowsay-off.
Preparing to unpack .../cowsay-off_3.03+dfsg2-3_all.deb ...
Unpacking cowsay-off (3.03+dfsg2-3) ...
Setting up cowsay (3.03+dfsg2-3) ...
Setting up cowsay-off (3.03+dfsg2-3) ...
Processing triggers for man-db (2.7.6.1-2) ...

Using Cowsay in Linux

Just type "cowsay" followed by a few words and you'll get something like this:

Screen Shot 2019-06-10 at 11.12.51.png

Changing the cow appearance in cowsay

From the cowsay man page:

There are several provided modes which change the appearance of the cow depending on its particular emotional/physical state. The -b option initiates Borg mode; -d causes the cow to appear dead; -g invokes greedy mode; -p causes a state of paranoia to come over the cow; -s makes the cow appear thoroughly stoned; -t yields a tired cow; -w is somewhat the opposite of -t, and initiates wired mode; -y brings on the cow's youthful appearance.

Here's an example of one of these options:

Screen Shot 2019-06-10 at 11.19.50.png

It's also possible to just specify the charecters to be used for the eyes of the cow, -e option needs to be followed by the two characters you want to seeScreen Shot 2019-06-10 at 12.14.51.png:

That's it for today, it's been fun!

See Also

Advanced Hardware Information for Raspberry Pi

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Screen Shot 2019-06-02 at 23.59.26.png

I've just learned about a really cool command for Raspbian OS, available in recent (Debian 9.0 based and later) Raspbian OS releases: pinout command shows you a visual presentation of what hardware configuration your Raspberry Pi has.

Simply type pinout, you don't even need to use sudo. You'll see output consisting of 3 parts that are so visual that I'll screenshot two of them to show you exactly what to expect.

Pinout command for Rasbian OS – Raspberry Pi schematics

First part of the otuput looks really cool – it shows you the model name and the system board layout – where power and HDMI connections, where Ethernet port is and where to plug in USB:

Screen Shot 2019-06-02 at 23.57.00.png

Then you get the second part of the output, which is additional hardware info about your Raspberry Pi:

Revision : a01041
SoC : BCM2836
RAM : 1024Mb
Storage : MicroSD
USB ports : 4 (excluding power)
Ethernet ports : 1
Wi-fi : False
Bluetooth : False
Camera ports (CSI) : 1
Display ports (DSI): 1

Finally, the last part of the output of the pinout command is actually the pinouts layout for the GPIO part of Raspberry Pi plaform:

Screen Shot 2019-06-03 at 00.09.18.png

See Also

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