How to pivot_root

1. Stop all uneeded services systemctl isolate rescue-ssh.target

2. Create the new / on ramdisk mkdir /tmp/tmproot && mount none /tmp/tmproot -t tmpfs

3. Create all the base directories mkdir /tmp/tmproot/{proc,sys,usr,var,run,oldroot,root}

4. Copy the base symlink cp -ax /{bin,etc,mnt,sbin,lib} /tmp/tmproot/

5. Copy /dev cp -a /dev /tmp/tmproot/dev

6. Copy the libs for services lsof -Fn / | grep ^n/ | cut -c2- | sort -u | grep /usr | rsync --files-from=- / /tmp/tmproot/

7. Copy other libs and binaries needed

   ldd /usr/bin/{wget,gzip,dd,mount,ls,cp,cat} | grep -o '/lib[^ ]*' | sed 's/^/\/usr/' | xargs -n1 readlink -f | rsync -v --files-from=- / /tmp/tmproot/

   ldd /usr/bin/{wget,gzip,dd,mount,ls,cp,cat} | grep -o '/lib[^ ]*' | sed 's/^/\/usr/' | rsync -lv --files-from=- / /tmp/tmproot/

   rsync -v /usr/bin/{wget,gzip,dd,mount,ls,cp,cat} /tmp/tmproot/usr/bin/

systemctl switch-root /tmp/tmproot/

OLLLD WAY NOT WORKING ANYMORE

unshare -m pivot_root /tmp/tmproot/ /tmp/tmproot/oldroot mount none /proc -t proc mount none /sys -t sysfs mount none /dev/pts -t devpts

wget -O - https://github.com/YunoHost/arm-images/releases/download/v2020.10/internetcube_4.0.8_v2020.10_lime2.img.gz | gzip -cd | dd iflag=fullblock bs=1M oflag=direct status=progress of=/dev/mmcblk0