pv permission denied, but dd works without error [duplicate]
Solution 1:
The redirections above are setup by your shell before forking and execing sudo. You may want something like the following:
sudo bash -c 'pv < /dev/sda > /dev/sdb'
This will cause bash to be run by sudo. Bash will execute the parameter to the -c arg as a command in that shell rather than running interactively.
The dd command worked because presumably you didn't use redirections with it.
Also, pv doesn't run above dd. The pv command does lots of things, including showing progress of its output to stdout or rate limiting its output.