$ Linux Command

Files

pv

Monitor the progress of data through a pipeline.

progresspipemonitoringthroughputtransferdd

Additional Notes

pv (Pipe Viewer) monitors the progress of data flowing through a pipeline. It shows the current transfer rate, total transferred data, elapsed time, estimated remaining time, and a progress bar. It sits between two commands in a pipe, measuring data as it passes through.

pv is invaluable for long-running operations like disk imaging (dd), file compression, database dumps, backups, and large file transfers where visual feedback helps estimate completion time. It adds no output of its own to the data stream, simply passing data through while displaying progress information on stderr.

Syntax

source | pv [options] [destination]
pv [options] [source] > destination
pv [options] source > destination

Parameters

  • source: Input file or device. If omitted, reads from stdin.
  • destination: Output file or device, specified via redirection or pipe.

Common Options

  • -p, --progress: Show the progress bar (default on).
  • -t, --timer: Show elapsed time.
  • -e, --eta: Show estimated time remaining.
  • -r, --rate: Show current transfer rate.
  • -a, --average-rate: Show average transfer rate.
  • -b, --bytes: Show total bytes transferred.
  • -n, --numeric: Numeric percentage output (machine-parseable).
  • -q, --quiet: No output. Useful for timing-only purposes.
  • -s size, --size size: Set the expected total data size for percentage calculation.
  • -L rate, --rate-limit rate: Limit the transfer to a maximum rate (e.g., 10m for 10 MiB/s).
  • -B bytes, --buffer-size bytes: Set the buffer size for transferring data.
  • -N name, --name name: Show a label before the progress display.
  • -F format, --format format: Specify the output format string.
  • -W, --wait: Wait for the first byte before displaying progress.
  • -D interval, --delay-start interval: Delay display by the specified number of seconds.
  • -c, --cursor: Use cursor positioning instead of newlines for updates.
  • -S, --stop-at-size: Stop transferring once the specified size is reached.

Examples

pv bigfile.tar.gz | tar xz

Monitor decompression of a tarball through a pipe.

pv backup.sql | mysql database

Monitor a MySQL database import.

pv /dev/sda > /dev/sdb

Monitor a raw disk copy with progress information.

dd if=/dev/sda | pv | dd of=/dev/sdb

Monitor a dd disk clone operation.

pv -s 10G bigfile.iso > /dev/null

Simulate reading a 10 GiB file, showing progress against the expected size.

cat largefile | pv -L 5m > /dev/null

Read a file but limit throughput to 5 MiB/s.

pv -n access.log | wc -l

Show numeric percentage progress, suitable for piping to dialog or zenity.

pv -tpreb /path/to/bigfile > /dev/null

Show all indicators: progress bar, timer, rate, ETA, and bytes.

pv -N "Copying" source.iso > dest.iso

Show a custom label before the progress display.

tar cf - /data | pv -s $(du -sb /data | awk '{print $1}') | gzip > backup.tar.gz

Create a compressed backup with accurate progress based on total bytes.

Practical Notes

  • pv does not modify data passing through it. It is safe to insert into any pipeline.
  • Use -s (--size) when pv cannot determine the total size automatically (e.g., from stdin). This enables percentage and ETA display.
  • For dd operations, replace dd status=progress with dd if=/dev/sda | pv | dd of=/dev/sdb for more detailed progress.
  • The rate limiter (-L) is useful for preventing backups from saturating network links or I/O.
  • pv reads from stdin and writes to stdout by default. If you provide a filename argument, it reads from the file.
  • Install with sudo apt install pv on Debian/Ubuntu or sudo yum install pv on RHEL/CentOS.
  • For monitoring in scripts, use -n for numeric output and parse the percentage value programmatically.