tldr/pages/common/pv.md

# pv

> Monitor the progress of data through a pipe.
> More information: <https://manned.org/pv>.

- Print the contents of the file and display a progress bar:

`pv {{path/to/file}}`

- Measure the speed and amount of data flow between pipes (`--size` is optional):

`{{command1}} | pv {{[-s|--size]}} {{expected_amount_of_data_for_eta}} | {{command2}}`

- Filter a file, see both progress and amount of output data:

`pv {{[-cN|--cursor --name]}} in {{path/to/file.txt}} | grep {{pattern}} | pv {{[-cN|--cursor --name]}} out > {{path/to/filtered_file.txt}}`

- Attach to an already running process and see its file reading progress:

`pv {{[-d|--watchfd]}} {{PID}}`

- Read an erroneous file, skip errors as `dd conv=sync,noerror` would:

`pv {{[-EE|--skip-errors --skip-errors]}} {{path/to/faulty_media}} > {{path/to/image.img}}`

- Stop reading after reading specified amount of data, rate limit to 1K/s:

`pv {{[-L|--rate-limit]}} {{1K}} {{[-S|--stop-at-size]}} {{maximum_file_size_to_be_read}}`

- Calculate hash (MD5, SHA1, SHA256, etc) of a large file and show progress:

`pv {{path/to/file}} | {{sha256sum}}`