While creating a level-0 archive I can do this:  tar -cf - . | pv -s $(du -sb . | awk '{print $1}') | gzip > out.tgzBut in case of a level-1 (incremental) archive, I don't know beforehand what the size of data to be archived will be.So I can't give that value to pv with the -s parameter (or have any idea about how long it'll take). What can be done?
How to display progress bar for tar incremental archives?
tar