Shell command: pv

pv (pipe viewer) displays the progress of data flowing through a pipeline

pv needs to be inserted between two commands in a pipeline. It will then read stdin and pass it to its stdout while shoing progress information on standard error.

Display progress of a file being gunzipped:

$ zcat boot.img.gz | pv > boot.img

Measure how fast data can be read from /dev/zero and written to /dev/null:

$ pv /dev/zero > /dev/null