Raspberry PI: Create system partition image to an external drive

create_image.sh

#!/bin/bash

# Example: ./create_image.sh /mnt/raspios-$(date "+%Y%m%d").img

#helper function
log_message()
{
    LOGPREFIX="[$(date '+%Y-%m-%d %H:%M:%S')][$(basename $0)]"
    MESSAGE=$1
    echo "$LOGPREFIX $MESSAGE"
}

#check for errors
check_errors()
{
    EXITCODE=$1
    if [[ ${EXITCODE} -ne 0 ]]; then
        log_message "ERROR: Exit code ${EXITCODE} , check the ouput for details."
        exit 1
    fi
}

#TARGET="/media/pi/PEN 64GB/raspios-preinstalled-`date "+%Y%m%d"`.img.gz"
TARGET=$1

if [ $# -eq 0 ]
  then
    log_message "Usage: $0 /path/to/myimage.img"
    exit 1
fi

log_message "Creating system partition backup to ${TARGET} ..."

set -o pipefail
dd bs=4M if=/dev/mmcblk0 conv=sync,noerror | pv -rabept --size $(lsblk -b | grep mmcblk0 | grep "disk" | awk '{ print $4 }')  > "${TARGET}"
check_errors $?

#dd bs=4M if=/dev/mmcblk0 conv=sync,noerror | pv -rabept --size $(lsblk -b | grep mmcblk0 | grep "disk" | awk '{ print $4 }') | gzip > "${TARGET}"

log_message "finished."