Show progress bar with `pv` and `pixz` about pixz

[vasi]

Things like that ought to work ok. I just did this (on OS X):

vasi$ SIZE=`du -sk trusty.pvm | cut -f 1`
vasi$ tar cf - trusty.pvm | pv -barpet -s ${SIZE}k | pixz > trusty.tpxz

Can you explain what happens when you try something like this? In what way does it not work?

[vasi]

Also, note that the rate estimates that pv gives may not be accurate at the start, because of how tools like pixz work.

For example, say you run pixz -9, and your CPU reports 8 cores. Pixz's queue size will be ceil(1.3 * nCores + 1) = 11, and for -9 the block size will be 128 MiB. So pixz will start by reading 12 * 128 MiB = 1.5 GiB before compression really gets started! This makes pv report a super high transfer rate. Afterwards, pixz will only read more as blocks are fully compressed, so the transfer rate will bounce around between zero and your disk's maximum rate. If you use the -a option to pv, it will show the average rate, which will eventually become reasonable.

[joelostblom]

Hey, thanks for the reply and sorry for not being more specific initially.

With "not working", I was referring to that the progress bar was not being displayed in the terminal. I did wait for a while before aborting, and it did show up when using pigz and waiting for a much shorter amount of time. However, I tried again with pixz and now the progress bar does show up eventually, it just takes much longer than with pigz (40 s instead of 1-2 s on a 2.3 GB folder), which I guess is due to the increased compression rate.

Thanks again for the reply and for pointing out the -a option.