If myfile is increasing over time, I can get the number of line per second using
tail -f | pv -lr > /dev/null
It gives instantaneous speed, not average.
How can I get the average speed (i.e the integral of the speed function v(t) over the monitoring time).
With pv 1.2.0 (December 2010) and above, it's with the -a option:
Here with both current and average, line-based:
$ find / 2> /dev/null | pv -ral > /dev/null
[6.28k/s] [70.1k/s]
With 1.3.8 (October 2012) and newer, you can also use -F/--format with %a:
$ find / 2> /dev/null | pv -lF 'current: %r, average: %a' > /dev/null
current: [4.66k/s], average: [ 218k/s]
Note that tail -f starts by dumping the last 10 lines of the file. Use tail -n 0 -f file | pv -la to avoid that bias in your average speed calculation.
