UNIX Tools: pipe viewer (pv) – monitor the progress of data through a pipe

Pipe Viewer (pv) allows a user to see the progress of data through a pipeline, by giving information such as time elapsed, percentage completed (with progress bar), current throughput rate, total data transferred, and estimated time of arrival.

pv can be inserted into any normal pipeline between two processes to give a visual indication of how quickly data is passing through, how long it has taken, how near to completion it is, and an estimate of how long it will be until completion.