pv is a Unix pipe monitoring application. (And this is copy of the much older original)
You can use it in places where a progressbar, or at least a flow rate meter, would be handy. Some handy examples:
# Is it still transferring or did something freeze?
docker save excelsior | pv | ssh [email protected] "docker load"# Why doesn't gzip have a progressbar already?
pv gigantic-file | gunzip | gawk '/size/ { x += $4 } END {print x}'