__linux_some_tricks.sh

# Remove sparce space from qcow image
# https://serverfault.com/questions/432119/is-there-any-way-to-shrink-qcow2-image-without-converting-it-raw
qemu-img convert -O qcow2 source.qcow2 shrunk.qcow2



# show progress bar for tar 
# https://superuser.com/questions/168749/is-there-a-way-to-see-any-tar-progress-per-file
# note: it requires "pv" package to be installed
_folder=./folder
_target=target.tar.gz

tar cf - ${_folder} -P | pv -s $(du -sb ${_folder} | awk '{print $1}') | gzip > ${_target}