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cp -pRv --reflink=auto /source/folder /destination/folder

copy files and directories
-p same as –preserve=mode,ownership,timestamps
-R, -r, –recursive
copy directories recursively
-v verbose, show what is going on.

–reflink[=WHEN]
control clone/CoW copies.

This just copied 169GB of files in 20 seconds. This only works on supported filesystems, so for example by „#Btrfs, , 4.2, , , and “. See here.

Explainshell tells you this.

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I will not write a long explanation, just this short one.

The cronjob looks like this:

* * * * * sh -c 'flock -n /tmp/my.lockfile /home/user/scripts/ocr_pdf_scan.sh'

This will start sh (a shell, just like bash) and run the command after -c. The command flock will create a lock-file, to prevent that this cron job is started while there is still the previous cron jobs running.

The cron job runs every minute, so in crontab it has * * * * * (five stars in front of the command).

In the ocr_pdf_scan.sh I have this:

#!/bin/bash

find /home/user/scans/ocr -type f \( -iname "*.pdf" -and -not -iname "*_ocr.pdf" \) | while read file ; do OLDTimestamp=$(stat -c "%Y" "$file") && ocrmypdf -q -l deu+eng --rotate-pages --rotate-pages-threshold 8 -c -s "$file" /home/user/scans/ocr_ready/"$(basename "$file" ".pdf")_ocr.pdf" && touch -d @$OLDTimestamp /home/user/scans/ocr_ready/"$(basename "$file" ".pdf")_ocr.pdf" && rm "$file" ; done

exit 0

Edit 31.07.2023: Added the stat/touch part to reset the modification time after ocrmypdf processed the file.

This will search for all files ending in „*.pdf“ but not „*_ocr.pdf“, it will pipe these path and filenames through to the while read, which will execute for each found file the ocrmypdf for the path and file stored in $file and output to another folder, it will strip the .pdf from the filename and append „_ocr.pdf“ to the filename again.

I tried this with output to the same folder as well, it also works, but for some reason I set it up like this.

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Important

This fix can be applied before the reboot after the upgrade from Buster to Bullseye, if you missed it you need a MicroSD card reader and some Linux computer (another RaspberryPI would do) to edit the file.

In the file 

/etc/systemd/system/dhcpcd.service.d/wait.conf

there is a wrong path for the dhcpd, it has to be changed.

wrong (from buster):

/usr/lib/dhcpcd5/dhcpcd

correct and new on Bullseye:

/usr/sbin/dhcpcd

So you need to do this before the reboot, otherwise the RaspberryPi will not have a working WIFI or Ethernet connection after the reboot and will not allow you to login from remote by SSH.

If you still have the RaspberryPi running you can use the command from this Stackexchange comment as well.

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So to upgrade Raspbian, as it was previously called, from Buster to Bullseye went smooth an easy, I tried this with some Pi2B (armhf 32Bit) and with a Pi4. These two are headless systems, so I don’t know if this works well for any systems with window managers.

Better run these commands in screen, so when the SSH connection is interrupted you can reconnect and resume your work.

Edit: For the update there is a culprit, it will cause a problem with dhcpd, so before the reboot 13. (was point 12. before I added the remark below) please check this post.

Steps to update:

  1. sudo apt update
  2. sudo apt dist-upgrade -y
  3. sudo rpi-update
  4. sudo reboot
  5. sudo apt remove libc6-dev
  6. Edit the file /etc/apt/sources.list, change all occurrences of buster to bullseye.
  7. Edit the file /etc/apt/sources.list.d/raspi.list, change all occurrences of buster to bullseye.
  8. sudo apt update
  9. sudo apt install libgcc-8-dev gcc-8-base
    • Instead of sudo apt install better use my update script, just run ~/up „libgcc-8-dev gcc-8-base“ (incl. the „quotation marks“) and skip steps 8., 9., 10. and 11. It doesn’t matter when you already executed step 8..
  10. sudo apt dist-upgrade
  11. sudo apt autoclean
  12. Please edit the file /etc/systemd/system/dhcpcd.service.d/wait.conf, change the path in there from /usr/lib/dhcpcd5/dhcpcd to /usr/sbin/dhcpcd, see here for long version.
  13. sudo reboot

Somewhere along the way there will be a warning that „libc6-dev“ can not be upgrade (or so) as it breaks „libgcc-8-dev“, this is the reason for step 5. and 9..

Edit: On the Pi4 I got:

The following packages have unmet dependencies:
 libgcc1 : Depends: gcc-8-base (= 8.3.0-6+rpi1) but 8.4.0-7+rpi1 is to be installed

Which I solved by „sudo apt-get remove libgcc1“ and then I just restarted with either point 8. from above, but in my case with „~/up libgcc-8-dev“.

I prefer to update or install packages with this script.

first inspiration from here.

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  1. Add key
curl https://ftp-master.debian.org/keys/archive-key-10.asc | gpg --import 
gpg --export DC30D7C23CBBABEE | apt-key add -

The fingerprint (DC30D7C23CBBABEE) given is the one that the first command outputs, which is the fingerprint of the key downloaded by curl.

2. Add repo

echo "deb http://deb.debian.org/debian buster-backports main" |sudo tee /etc/apt/sources.list.d/deb_buster_backports.list
  1. run apt update/upgrade
  2. Install tor, I did this by:
apt-get install -o Dpkg::Options::="--force-confold" -y tor
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This is a solution for a , some without swap of some machine setup without swap where you need swap for something without wanting to fiddle with the drive partitions or so.

This is a quick and dirty „short manual“ for based environments (such as , or ).

First run this:

cat > dphys-swap.sh << EOF
#!/bin/bash
#~/up
apt-get install dphys-swapfile
echo "CONF_SWAPSIZE=2048"|tee -a /etc/dphys-swapfile
dphys-swapfile setup
dphys-swapfile swapon
systemctl restart dphys-swapfile.service
systemctl status dphys-swapfile.service
free -h
EOF

This will just create a short with the needed commands to run to get setup and running. Please alter the number 2048 to your need, it is the size of the swap memory that will be setup. The size of the swap should most likely by equal to the real memory installed, sometimes twice the size seems to be a good choice too.

If you don’t know your memory size you can find it out by running the command „free -h“, which will print the size of the physical memory installed and the below this the swap size(s).

After pasting the above code into your shell, which will create a file called „dphys-swap.sh“ in the current folder (you should be in your home folder!!), you need to make the shell script „dphys-swap.sh“ executable by running:

chmod +x dphys-swap.sh

Then you need to run the script like this:

sudo ~/dphys-swap.sh

It will ask for some confirmation(s) to install certain packages.

The last commands will output the status of the systemd service „dphys-swapfile.service“ and the last line will show you the memory and swap size again.

Remark:
In the script above I use „up“, my full update of the system. I just blogged that one too, have a look here.

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I have this small script deployed on any of my based systems, it just does all the update, upgrade, dist-upgrade, autoremove and autoclean in one run. 

#!/bin/sh 

if [ $# -eq 0 ]; then
  sudo sh -c "apt-get update && apt-get upgrade && apt-get dist-upgrade && apt-get update && apt-get autoremove && apt-get autoclean"
else
  sudo sh -c "apt-get update && apt-get upgrade && apt-get dist-upgrade && apt-get update && apt-get install $@ && apt-get autoremove && apt-get autoclean"
fi

I have this script deployed in a lazy manner, I just have it sitting in my users home folder and called it „up“, I did do a „chmod +x up“ and just start it like this:

~/up

It also accepts one several package names as an arguments and that be called like this:

sudo ~/up package1,package2

This will then install „package1“ and „package2“.

I am not sure where I found this, but I surely did find this somewhere in the internet and just took it from there, you thanks to who ever put this together.