datag / kbase

Personal knowledge base

kbase

GPT

(source)

Backup

sgdisk --backup=<file> <device>

Restore

sgdisk --load-backup=<backup file> <target device>

Images

Create empty sparse file

truncate -s 128G test.img

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Dig holes (make sparse again)

fallocate -v -d test.img

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fsarchiver backup

fsarchiver savefs test.fsa /dev/mmcblk0p1 -v -j8 -Z15

fsarchiver "extract"

truncate -s 10G test.img
losetup /dev/loop1 test.img    # OR find and use free loop device: losetup -f --show test.img
fsarchiver restfs test.fsa id=0,dest=/dev/loop1

Grub2

Reinstall on system

https://superuser.com/questions/376470/how-to-reinstall-grub2-efi#comment1546454_721045

sudo grub-install --target=x86_64-efi --efi-directory=/boot/efi

Reinstall grub2 using another system:

mkdir /mnt/rootfs
mount /dev/sdX1 /mnt/rootfs
mount /dev/sdX2 /mnt/rootfs/boot/efi
mount -t proc proc /mnt/rootfs/proc
mount --rbind /sys /mnt/rootfs/sys   # use rbind so /sys/firmware/efi/efivars is populated
mount --rbind /dev /mnt/rootfs/dev
chroot /mnt/rootfs /bin/bash

(chroot) export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin   # depending on system
(chroot) grub-install /dev/sdX
(chroot) update-grub2

Maintenance free custom Gub2 screen

https://help.ubuntu.com/community/MaintenanceFreeCustomGrub2Screen

Fix issue with multi-boot

https://help.ubuntu.com/community/MaintenanceFreeCustomGrub2Screen#If_you_multiboot_mutiple_Linux_installs_and_want_one_Grub_to_control_all_of_your_OSs

On secondary system do:

sudo dpkg-reconfigure grub-efi-amd64     # if not installed, install first
# unselect installing into device

Secure boot thumb drive without valid signature

1. rename original bootx64.efi to loader.efi
2. rename PreLoader.efi to bootx64.efi
3. and it put HashTool.efi in /efi/boot directory
4. (if "Failed to start loader"): "Enroll Hash" for "loader.efi"

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ODROID MBR & bootloader backup

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sfdisk -l /dev/mmcblk0
# find start of first partition, e.g. 49152
dd if=/dev/mmcblk0 of=mbr-bootloader.bin bs=512 count=49151   # start minus 1 sector

Restore bootloader only:

dd if=mbr-bootloader.bin of=/dev/mmcblk0 bs=512 skip=1 seek=1

Restore bootstrap code:

dd if=mbr-bootloader.bin of=/dev/mmcblk0 bs=446 count=1

BTRFS

btrfs fi usage /media/dominik/DATA
btrfs balance start -dusage=70 -musage=70 /media/dominik/DATA
btrfs balance status /media/dominik/DATA

rsync

rsync -ahSAXH --delete --info=progress2 [ssh-host:]src/ dst

# -a archive
# -h human
# -S sparse
# -A ACLs
# -X xattrs
# -H hard links

Graphics

Remove EXIF meta data

# remove all meta data
exiftool -all= my-image.jpg

# remove meta data and replace image
exiftool -overwrite_original -all= my-image.jpg

Audio

Rip YouTube video/playlist to MP3

youtube-dl -x --audio-quality 0  --audio-format mp3 https://www.youtube.com/watch?v={YT_CODE}

VHS video capture (w/o deinterlacing)

ffmpeg -f alsa -thread_queue_size 4096 -ar 48000 -ac 2 -i hw:1 -f v4l2 -thread_queue_size 4096 -input_format yuyv422 -framerate 25 -i /dev/video0 -vf format=yuv420p -c:v libx264 -preset slow -crf 21 -vprofile baseline -c:a aac -y video.mp4