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Linux installation and initial configuration

by Wintermute0110

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In this chaper I cover the installation of Ubuntu Linux on a PC architecture with an Intel graphics card. After finishing this chapter you will have a working home theater personal computer (HTPC) with the network configured and ready to install Kodi or EmulationStation as your frontend and optionally some emulators such as Retroarch, MAME or Mednafen.

In this guide I assume you have a Linux desktop or laptop as your main computer. Windows users will need to google a bit for additional procedures in some steps of this guide. For example, to connect to the HTPC computer using SSH Linux users can do it natively, Windows users need to use additional software such as PuTTY.

During normal use of your HTPC your will control it with a gamepad, ether if you choose Kodi or EmulationStation as the main frontend. However, a keyboard and mouse will be required during the installation and configuration. You can use the wireless interface to connect to the internet, however during the installation a wired connection is necessary to setup the wifi interface. If you want to store your media in a NAS I strongly recommend to connect the NAS and the HTPC with a wired Ethernet connection.

This tutorial focuses on using an Intel video card because it is available as an integrated video card in 99% of al PCs and usually works plug-and-play. If you want to use your discrete AMD or NVidia card you need to do some changes related to the video configuration.

In Linux/Unix usually here are several ways of doing things, each with its pros and cons. In this guide I will use systemd as much as possible to configure services. This sometimes makes the configuration slighly more complicated that alternatives but saves memory and resources in your HTPC which is good for low-end PCs.

NOTE It is important that you switch off your monitor or TV BEFORE your HTPC. The monitor/TV must be on before the HTPC is started so the HTPC can autodetect the graphic resolution and refresh rate automatically. Failure to do this may result in corrupted graphics. In such case, with the monitor/TV on simply reboot your HTPC.

User name and HTPC computer name

When you install Ubuntu Linux you are asked for a regular or unprivileged user name. In this guide I use the kodi user name with home directory /home/kodi. Note that you can choose the user name you want, however BE AWARE that you will need to change some configuration files and file path names to mach the user name.

In this guide your HTPC computer will be named htpc. Again, you can use the name you want but pay attention because you will need to change some commands and/or configuration files to match your HTPC name. For example, to connect to your HTPC computer using SSH you can use kodi@htpc where kodi is the user name and htpc is the HTPC computer name. If you use different values for the user name or computer name you will need to change or adapt the instructions of this guide accordingly.

Preparing the installation media

We will use a USB drive to install Ubuntu 20.40 Focal Fossa.

Step 1) Download the installation ISO image

Use one of the Ubuntu mirrors to download the ISO image of Ubuntu 20.04 LTS Focal Fossa 64-bit Server install image. The server install image installs only the minimum set of packages required to run Linux, as oppossed to the Ubuntu Desktop image which installs a lot of clutter software you do not need on an HTPC.

Ubuntu 20.04 LTS (Focal Fossa) installation images

Step 2) Create a bootable USB drive

Plug in the USB drive and use lsblk to learn the USB drive name. For example:

wintermute@pc:~$ lsblk
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
sdb      8:16   0 931.5G  0 disk 
└─sdb1   8:17   0 931.5G  0 part /home
sdc      8:32   0 447.1G  0 disk 
├─sdc1   8:33   0   953M  0 part /boot
├─sdc2   8:34   0  22.4G  0 part [SWAP]
└─sdc3   8:35   0 423.9G  0 part /
sdd      8:48   1   3.8G  0 disk 
├─sdd1   8:49   1   1.8G  0 part 
└─sdd2   8:50   1   3.7M  0 part

One trick is to execute lsblk before you insert the USB drive, and then again with the USB drive inserted. The device name of the USB drive is the new one that show up. Dismount any partitions of the UBS drive if they are mounted with umount, in some systems partitions are mounted automatically when you insert removable drives.

Use dd to copy the installation ISO image into the USB drive. sdX is the device name of the USB drive, substitute the X with the appropiate letter. BE CAREFUL dd is a destructive command that will erase all the contents of the USB drive. If you specify the wrong device name you can wipe the hard disk of your computer. The sync command after dd is not strictly necessary but better safe than sorry.

root@pc:~# dd bs=4M conv=fdatasync status=progress if=path/to/input.iso of=/dev/sdX
root@pc:~# sync

ask ubuntu: Create a bootable USB drive

Installation of Ubuntu Linux

Connect the NUC HDMI port to your TV or monitor. Connect a USB keyboard. The keyboard will be used for the installation and configuration. During normal use you will use a gamepad to control Kodi or EmulationStation. However, a keyboard may be needed very occasionally for configuration purposes. When configuring the X server (graphical environment) a mouse will be needed. Finally, connect the USB drive you created in the previous step. To setup the wireless interface we need to download some software not installed by default, so during the installation process connect an Ethernet cable to the wired Ethernet adapter.

Switch on the power on the NUC. If necessary access the BIOS and configure it to boot from the USB drive. If you experience problems during the installation have a look to the Install Ubuntu Server guide.

(Optional) SSD hard disks

If you installed Linux in a SSD hard disk read this section. You can skip it otherwise.

In Ubuntu Focal Fossa, filesystems are mounted by default with the option relatime. Triming is set to run once a week with a systemd timer and its associated service on all hard disk that support it. This is the recommended behavior for SSDs in 2020 in Debian and other major distributions.

Step 1) Verify trimming and mounting options

To verify the mounting options of currently mounted filesystems use cat /proc/mounts | grep /dev/. Check that filesystems have the option relatime.

Now verify that trimming is set to run once a week:

$ systemctl status fstrim.timer
COMPLETE ME

Step 2) Lower usage of swap

The swappiness parameter controls the tendency of the kernel to move processes out of physical memory and onto the swap disk.

$ cat /proc/sys/vm/swappiness
60

The default setting in Ubuntu is swappiness = 60. A value of 5 is recommended for SSDs. Edit the file $ sudo nano /etc/sysctl.conf and at the and append:

# Reduce swappiness.
vm.swappiness=5

Save the file, reboot the system and verify that the swappiness is now 5.

ask ubuntu: Is TRIM enabled on my Ubuntu 18.04 installation?

Debian wiki: SSDOptimization

SSD: how to optimize your Solid State Drive for Linux Mint and Ubuntu

Ubuntu help: What is swappiness and how do I change it?

Initial unneeded software cleanup

RATIONALE The less unnecessary software the better, your HTPC will consume less memory and will boot faster.

Step 1) Remove snap

To remove the new Ubuntu package manager called snap type the following commands. This will completely remove snap, snapd, all installed snap packages and their data, and never again suggest snap packages in the software store.

$ sudo rm -rf /var/cache/snapd/
$ sudo apt autoremove --purge snapd

Step 2) Remove DM Multipath

Linux DM Multipath is used in servers in a datacenter for load-balancing an redudancy of block devices. We don’t need this in an HTPC.

$ sudo apt autoremove --purge multipath-tools

NOTE The virtual package ubuntu-server and some others will also be removed.

Step 3) Remove Unattended Upgrades

You want to make sure your HTPC does not automatically upgrade software at the most incovenient moment.

$ sudo apt autoremove --purge unattended-upgrades

Network configuration

If you are using the wired Ethernet port to connect to the internet follow the steps in the next subsection. If you want to use WiFi to connect to the Internet then first configure the wired interface and after that proceed with the configuration of the wireless adapter. The reason is that we need to download the wpasupplicant package which is not installed by default and it is required for the wireless adapter to work.

Wired Ethernet interface configuration

RATIONALE The wired interface should be detected and configured during the installation process. However, by default Ubuntu Focal Fossa uses netplan to manage the network and we will switch to systemd-networkd.

IMPORTANT This steps must be done logged into the system with a keyboard. Do not use a SSH connection!

Step 1) Identify the name of the wired interface

kodi@htpc:~$ ls /sys/class/net
eno1   lo   wlp0s20f3

Wired interface names start with en. In this case the interface name is eno1.

Step 2) Remove netplan

Some extra packages will be removed as well as they are not needed.

$ sudo apt autoremove --purge nplan netplan.io

Step 3) Create the systemd-networkd configuration file

Verify that the directory /etc/systemd/network is empty with ls -l /etc/systemd/network. Create the following configuration file with $ sudo nano /etc/systemd/network/20-wired.network. Change the line Name=eno1 to mach the name of your wired interface name.

# File /etc/systemd/network/20-wired.network

[Match]
Name=eno1

[Network]
DHCP=ipv4

Step 4) Enable the systemd-networkd service

$ sudo systemctl enable systemd-networkd.service

Step 5) Verify that systemd-resolved is runnning

Check that /etc/resolv.conf

$ ls -l /etc/resolv.conf
.....

Verify that systemd-resolved is running with $ systemctl status systemd-resolved.service. You should see a line like Active: active (running) since .... If not, then enable the service with $ sudo systemctl enable systemd-resolved.service.

Step 6) Reboot the machine and test the network

Reboot the machine with $ reboot. Then, test the network with:

$ networkctl
COMPLETE
$ ip a
COMPLETE
$ ping google.com
COMPLETE

Press Ctrl + C to stop the ping command.

Step 7) Install the package wpasupplicant

This is only required if you plan to configure the wireless interface.

$ sudo apt install wpasupplicant

archlinux wiki: Systemd-networkd

(Optional) Wireless interface configuration

Step 1) Identify the name of the wifi interface

kodi@htpc:~$ ls /sys/class/net
eno1   lo   wlp0s20f3

Wireless interface names start with w. In this case the interface name is wlp0s20f3.

Step 2) Create the systemd-networkd configuration file

Create the following configuration file with $ sudo nano /etc/systemd/network/30-wireless.network. Change the line Name=wlp0s20f3 to mach the name of your wired interface name.

# File /etc/systemd/network/30-wireless.network

[Match]
Name=wlp0s20f3

[Network]
DHCP=ipv4

Step 3) Configure wpasupplicant

Create the wpasupplicant configuration file with $ sudo nano /etc/wpa_supplicant/wpa_supplicant.conf. Change "MYSSID" and "passphrase" with your SSID and network password. It is important to keep the quotes.

# File /etc/wpa_supplicant/wpa_supplicant.conf

ctrl_interface=/run/wpa_supplicant
ap_scan=1
fast_reauth=1

# network section generated by wpa_passphrase
network={
    ssid="MYSSID"
    psk="passphrase"
    key_mgmt=WPA-PSK
}

Now create the systemd service to enabled wpasupplicant to control your wireless interface with $ sudo nano /etc/systemd/system/wpa-wlp0s20f3.service. Do not forget to change the name of your wireless interface to match your system in all places in the configuration file and also in the configuration file name:

# File /etc/systemd/system/wpa-wlp0s20f3.service

[Unit]
Description=WPA supplicant for interface wlp0s20f3
DefaultDependencies=no
Requires=sys-subsystem-net-devices-wlp0s20f3.device
After=sys-subsystem-net-devices-wlp0s20f3.device
Before=network.target
Wants=network.target

[Service]
Type=simple
ExecStart=/sbin/wpa_supplicant -c /etc/wpa_supplicant/wpa_supplicant.conf -iwlp0s20f3

Step 4) Configure systemd-resolved

Check if /etc/resolv.conf points to the systemd-resolved file:

$ ls -l /etc/resolv.conf
COMPLETE ME

If not, execute the following commands:

# rm /etc/resolv.conf
# ln -s /run/systemd/resolve/resolv.conf /etc/resolv.conf

Step 4) Enable systemd services and configure resolved

First enable all the systemd services:

# systemctl enable wpa-wlp0s20f3.service
# systemctl enable systemd-networkd.service
# systemctl enable systemd-resolved.service

Check your configuration.

$ systemctl is-enabled wpa-wlp0s20f3.service
$ systemctl is-enabled systemd-networkd.service
$ systemctl is-enabled systemd-resolved.service

Step 5) Reboot the machine and test the network

Reboot the machine with $ reboot. After rebooting test the network as described in the previous section but look for the wireless interface instead of the wired one.

archlinux wiki: wpa_supplicant

Manjaro: How to use systemd-networkd to manage your wifi

Installing software

Now install some software packages including the X server (graphical environment).

root@htpc:~# apt install alsa-utils lm-sensors udisks2 avahi-daemon
root@htpc:~# apt install dbus-x11 openbox
root@htpc:~# apt install xorg xserver-xorg-legacy lxterminal mousepad
root@htpc:~# apt install va-driver-all i965-va-driver-shaders
root@htpc:~# apt install mesa-utils vulkan-tools vainfo
root@htpc:~# apt install xdg-utils

lxterminal is a minimalist terminal emulator for the X server with few dependencies. mousepad is a good text editor for the X server with few dependencies. xdg-utils installs xdg-screensaver which is used by Retroarch to control the screensaver.

NOTE The packages ssh, software-properties-common, linux-firmware, git, pastebinit are installed by default in Ubuntu Focal Fossa server.

Basic HTPC configuration

Allow anybody to start the X server:

root@htpc:~# dpkg-reconfigure xserver-xorg-legacy

Now edit /etc/X11/Xwrapper.config and add the following into a new line at the end of the file:

needs_root_rights=yes

Give privileges to the kodi user you created in the installation:

root@htpc:~# usermod -a -G cdrom,audio,video,plugdev,users,dialout,dip,input kodi

You can check the groups the user kodi belongs with:

root@htpc:~# groups kodi
kodi : kodi adm ...

Now create the file /home/kodi/.xinitrc that will be used by startx.

# File /home/kodi/.xinitrc

# Execute an Openbox window manager session.
# Openbox will execute the contents of /home/kodi/.config/openbox/autostart
exec openbox-session

Now create the file /home/kodi/.config/openbox/autostart. Remeber that the lines that start with a # are comments and are not necessary.

# File /home/kodi/.config/openbox/autostart
# Commands here are blocking. Use a trailing & to run concurrently.

# Enable full color range in the connected display.
OUTPUT=`xrandr -display :0 -q | sed '/ connected/!d;s/ .*//;q'`
xrandr -display :0 --output $OUTPUT --set "Broadcast RGB" "Full"

# Set the background to black.
xsetroot #000000

# Disable the screensaver and the power management.
# To check the status of the screensaver use the command `$ xset q`
# If you connect via SSH execute `$ export DISPLAY=:0` before commands
# like `xset` or `glxinfo`.
xset s off -dpms

# Launchg a terminal emulator
lxterminal &

At this point you can test the X server (graphical interface). You will need a mouse to use the X server.

kodi@htpc:~$ startx

The screen will turn black (don’t panic) and you will see the mouse pointer in the middle of the screen. With a right click you can open the Openbox context menu and launch a graphic terminal. In the graphic terminal type glxinfo, vulkaninfo and vainfo to check that the OpenGL acceleration, Vulkan acceleration and VA-API are working well.

Openbox running a terminal

To exit the X server bring up the Openbox context menu with a mouse right click and click on Exit. You will return to the text console.

ArchLinux wiki Display Power Management Signaling

Set permissions to shutdown, suspend and mount disks

Kodi and EmulationStation will use D-Bus to reboot and power off your HTPC and it is necessary to give privileges to the Kodi user. Create the file /etc/polkit-1/localauthority/50-local.d/custom-actions.pkla.

# File /etc/polkit-1/localauthority/50-local.d/custom-actions.pkla root:root 644
[Actions for kodi user]
Identity=unix-user:kodi
Action=org.freedesktop.login1.*;org.freedesktop.udisks2.*
ResultAny=yes
ResultInactive=yes
ResultActive=yes

[Untrusted Upgrade]
Identity=unix-user:kodi
Action=org.debian.apt.upgrade-packages;org.debian.apt.update-cache
ResultAny=yes
ResultInactive=yes
ResultActive=yes

Start The X server when the machine boots

Create the MyOpenBox.service file:

# File /etc/systemd/system/MyOpenBox.service
[Unit]
Description = Run xinit with Openbox-session and D-Bus
Requires = dbus.service
After = systemd-user-sessions.service sound.target network-online.target

[Service]
User = kodi
Group = kodi
Type = simple
PAMName = login
ExecStart = /usr/bin/xinit /usr/bin/dbus-launch --exit-with-session /usr/bin/openbox-session -- :0 -nolisten tcp vt7
Restart = on-abort

[Install]
WantedBy = graphical.target

Now replace the current display-manager.service with the MyOpenBox.service:

# rm -f /etc/systemd/system/display-manager.service
# ln -s /etc/systemd/system/MyOpenBox.service /etc/systemd/system/display-manager.service

Enable the HTPC to start the X server at boot time by setting graphical.target as the default target with # systemctl set-default graphical.target. Check the default target with:

$ systemctl get-default
graphical.target

With the previous setting your HTPC will boot in the X server (graphical environment). If for some reason you want to boot in the text console # systemctl set-default multi-user.target. For example, it may be useful to boot in the text console when you are setting up /home/kodi/.config/openbox/autostart file to run EmulationStation or Kodi and once everything is working OK then you enable booting in the graphical environment.

(Optional) Connecting to the HTPC with SSH

In your Linux desktop/laptop edit the file /etc/hosts and append at the end.

192.168.0.20   htpc

Change the IP address to the one you have assigned in your router to the HTPC computer. I recommend to assign a static IP address so it does not change when you reboot your computers. To learn the MAC address of the WiFi interface of your HTPC use the ip a command in the HTPC. After that, you can connect to your HTPC with ssh kodi@htpc.

If you don’t modify /etc/hosts then you need to use the IP adress of your HTPC instead of the network name.

(Optional) Change priority of user kodi

Edit /etc/security/limits.conf and add before the end. Remember kodi is the username, not the application. This will allow your user to get the audio thread a bit more priority.

kodi             -       nice            -1

(Optional) Changing the time zone

By default the UTC is used. Kodi and many emulators require that the time is correctly set to work properly. To set the correct time execute:

root@htpc:~# dpkg-reconfigure tzdata

By default systemd automatically sets the time of your HTPC from the network so the only thing you need to do is to configure the correct time zone where you are located.

archlinux wiki: systemd-timesyncd

(Optional) Install Plymouth

Plymouth enables a graphical boot process as opposed to systemd printing lots of text. Also, by loading the module i915 for Intel video cards into your initramfs (the first step in the boot process) you enable kernel video mode (KMS) setting which avoids flickering in your display during the boot process.

Plymouth seems to be already installed but it is not enabled in Ubuntu Focal Fossa. It doesn’t hurt to make sure it is installed:

root@htpc:~# apt install plymouth plymouth-theme-ubuntu-logo plymouth-themes

Edit the file /etc/initramfs-tools/modules and add at the end:

# Intel graphics card.
i915 modeset=1

Then update the initramfs with sudo update-initramfs -u

Edit the file /etc/default/grub and add the splash word to:

GRUB_CMDLINE_LINUX_DEFAULT="splash"

If there are more arguments then add splash at the end separated with one space from the previous word. Now execute sudo update-grub. You can check the current kernel command line with cat /proc/cmdline if you run into trouble.

To change the plymouth theme execute:

root@htpc:~# update-alternatives --config default.plymouth
root@htpc:~# update-initramfs -u

To search for themes use apt search plymouth theme and then install the themes you want with sudo apt install.

Plymouth documentation can be found in /usr/share/doc/plymouth/, to read it execute $ zless /usr/share/doc/plymouth/README.Debian.

(Optional) Change the console font size

The default console size is rather small and can be inconvenient if your HTPC is connected to a big screen or TV. To change the default console font execute:

root@htpc:~# dpkg-reconfigure console-setup

Make sure you choose UTF-8 as the encoding, choose the default in the character set, choose VGA as the font for the console, finally choose the 16x28 or 16x32 size. To roll back you changes and set the default values, execute dpkg-reconfigure console-setup and choose Fixed font and 8x16 size.