Replacing Bitmap In-Place

Sometime even the simplest application can cause the exception. For example let’s just open an image, edit it, and save it afterward. Something like this:

var image = new Bitmap("test.jpg");
// do something with image
image.Save("test.jpg");

This code will throw the really helpful “A generic error occurred in GDI+.” exception.

Fortunately, there is more than one way to skin this cat. Rather similar (and equivalent) code will work:

Bitmap image;
using (var stream = new FileStream("test.jpg", FileMode.Open)) {
    image = (Bitmap)Bitmap.FromStream(stream);
}
// do something with image
image.Save("test.jpg");

A slightly different embodiment of the same idea.

Appending to Certificate Bundle

When one needs to add an extra certificate to a certificate bundle, the first idea might be something like this:

cat example.pem >> /etc/ssl/certs/ca-bundle.crt

And that will work - if you are a root user. However, if you are just a sudoer, or God-forbid a cloud-user, you might find yourself up the creek without a paddle.

You see, sudo won’t simply do as it operates on the source and not the destination:

sudo cat example.pem >> /etc/ssl/certs/ca-bundle.crt
 -bash: /etc/ssl/certs/ca-bundle.crt: Permission denied

You might want to play with tee, but depending on your exact permissions that might fail also.

cat example.pem | sudo tee -a /etc/ssl/certs/ca-bundle.crt

However, one command that never fails is vi as it has quite a lot of code to work out writing to read-only files. And conveniently, we can script it too:

sudo ex +"r /opt/install/ca.pem" -scwq! /etc/ssl/certs/ca-bundle.crt

Yep, we essentially start vi, read the extra content into it, and then force-save it all.

Configuring Thumb Button on M720 Under Ubuntu

The most usable function I found for my mouse thumb button is actually Minimize window. When you combine it with Alt+Tab, it does wonders for fast window switching. Under Windows it’s trivial to configure this within Logitech Options. While not as easy in Linux, it’s actually not that hard either.

Since the Thumb button on most Logitech’s devices is not a mouse button but a key combination, we can use Ubuntu’s built-in Keyboard utility instead of remapping buttons. Or we can do it from command line equally easy:

gsettings set org.gnome.desktop.wm.keybindings minimize "['<Primary><Alt>Tab']"

If you really want to have quick switching, you might want to also disable animations:

gsettings set org.gnome.desktop.interface enable-animations false

With those two changes you have your thumb button configured.

PS: And yes, this works for MX Master too.

Remap M720 Mouse Buttons Under Ubuntu

M720 mouse has quite a few buttons. But remapping them under Linux is not necessarily the easiest thing in the world. For example, if one wants Forward and Backward buttons remapped to window left/right snap, there are a few things that need to be done manually.

First we need a few packages:

sudo apt install -y xbindkeys xautomation

Then we need to figure out which code our forward and backward keys are:

xev | grep -A 2 Button

In my case, these were 8 and 9 respectively.

Then we need to write mappings in ~/.xbindkeysrc:

"xte 'keydown Super_L' 'key Left' 'keyup Super_L'"
b:9

"xte 'keydown Super_L' 'key Right' 'keyup Super_L'"
b:8

And lastly, we need to restart xbindkeys:

killall xbindkeys 2>/dev/null
xbindkeys

If all went well, your buttons now know a new trick.

UEFI Install for Root ZFS Ubuntu 18.10

There is a newer version of this guide for Ubuntu 19.04.

Booting ZFS Ubuntu of MBR is story I already told. But what if we want an encrypted UEFI ZFS setup?

Well, it’s quite simple to previous steps and again just a derivation on ZFS-on-Linux project.

As before, we first need to get into root prompt:

sudo -i

Followed by getting a few basic packages ready:

apt-add-repository universe
apt update
apt install --yes debootstrap gdisk zfs-initramfs

Disk setup is quite simple with only two partitions:

sgdisk --zap-all             /dev/disk/by-id/^^ata_disk^^

sgdisk -n2:1M:+511M -t2:EF00 /dev/disk/by-id/^^ata_disk^^
sgdisk -n1:0:0      -t1:8300 /dev/disk/by-id/^^ata_disk^^

sgdisk --print               /dev/disk/by-id/^^ata_disk^^
 Number  Start (sector)    End (sector)  Size       Code  Name
    1         1050624        67108830   31.5 GiB    8300
    2            2048         1050623   512.0 MiB   8300

I believe full disk encryption should be a no-brainer so of course we set up LUKS:

cryptsetup luksFormat -qc aes-xts-plain64 -s 512 -h sha256 /dev/disk/by-id/^^ata_disk^^-part1
cryptsetup luksOpen /dev/disk/by-id/^^ata_disk^^-part1 luks1

Creating ZFS stays the same as before:

zpool create -o ashift=12 -O atime=off -O canmount=off -O compression=lz4 -O normalization=formD \
    -O xattr=sa -O mountpoint=none rpool /dev/mapper/luks1
zfs create -o canmount=noauto -o mountpoint=/mnt/rpool/ rpool/system
zfs mount rpool/system

Getting basic installation on our disks follows next:

debootstrap cosmic /mnt/rpool/
zfs set devices=off rpool
zfs list

And then we setup EFI boot partition:

mkdosfs -F 32 -n EFI /dev/disk/by-id/^^ata_disk^^-part2
mount /dev/disk/by-id/^^ata_disk^^-part2 /mnt/rpool/boot/

We need to ensure boot partition auto-mounts:

echo PARTUUID=$(blkid -s PARTUUID -o value /dev/disk/by-id/^^ata_disk^^-part2) /boot vfat noatime,nofail,x-systemd.device-timeout=5s 0 1 >> /mnt/rpool/etc/fstab
cat /mnt/rpool/etc/fstab

Before we start using anything, we should prepare a few necessary files:

cp /etc/hostname /mnt/rpool/etc/hostname
cp /etc/hosts /mnt/rpool/etc/hosts
cp /etc/netplan/*.yaml /mnt/rpool/etc/netplan/
sed '/cdrom/d' /etc/apt/sources.list > /mnt/rpool/etc/apt/sources.list

If you are dual-booting system with Windows, do consider turning off UTC BIOS time:

echo UTC=no >> /mnt/rpool/etc/default/rc5

With chroot we can get the first taste of our new system:

mount --rbind /dev  /mnt/rpool/dev
mount --rbind /proc /mnt/rpool/proc
mount --rbind /sys  /mnt/rpool/sys
chroot /mnt/rpool/ /bin/bash --login

Now we can update our software:

apt update

Immediately followed with locale and time zone setup:

locale-gen --purge "en_US.UTF-8"
update-locale LANG=en_US.UTF-8 LANGUAGE=en_US
dpkg-reconfigure --frontend noninteractive locales

dpkg-reconfigure tzdata

Now we install Linux image and basic ZFS boot packages:

apt install --yes --no-install-recommends linux-image-generic
apt install --yes zfs-initramfs

Since we’re dealing with encrypted data, our cryptsetup should be also auto mounted:

apt install --yes cryptsetup

echo "luks1 UUID=$(blkid -s UUID -o value /dev/disk/by-id/^^ata_disk^^-part1) none luks,discard,initramfs" >> /etc/crypttab
cat /etc/crypttab

Now we get grub started:

apt install --yes grub-efi-amd64

And update our boot environment again (seeing errors is nothing unusual):

update-initramfs -u -k all

And then we finalize our grup setup:

update-grub
grub-install --target=x86_64-efi --efi-directory=/boot --bootloader-id=ubuntu --recheck --no-floppy

Finally we get the rest of desktop system:

apt-get install --yes ubuntu-desktop samba linux-headers-generic
apt dist-upgrade --yes

We can omit creation of the swap dataset but I always find it handy:

zfs create -V 4G -b $(getconf PAGESIZE) -o compression=off -o logbias=throughput -o sync=always \
    -o primarycache=metadata -o secondarycache=none rpool/swap
mkswap -f /dev/zvol/rpool/swap
echo "/dev/zvol/rpool/swap none swap defaults 0 0" >> /etc/fstab
echo RESUME=none > /etc/initramfs-tools/conf.d/resume

If one is so inclined, /home directory can get a separate dataset too:

rmdir /home
zfs create -o mountpoint=/home rpool/data

Only remaining thing before restart is to create user:

adduser ^^user^^
usermod -a -G adm,cdrom,dip,lpadmin,plugdev,sambashare,sudo ^^user^^
chown -R ^^user^^:^^user^^ /home/^^user^^

As install is ready, we can exit our chroot environment and reboot:

exit
reboot

You will get stuck after the password prompt as our mountpoint for system dataset is wrong. That’s easy to correct:

zfs set mountpoint=/ rpool/system
exit
reboot

Assuming nothing went wrong, your UEFI system is now ready.

PS: There are versions of this guide using the native ZFS encryption for other Ubuntu versions: 21.10 and 20.04

PPS: For LUKS-based ZFS setup, check the following posts: 20.04, 19.10, and 19.04.