@dircategory Miscellaneous * PV: (pv). Monitor the progress of data through a pipe.

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Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.

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Overview

This is the documentation for pv, a terminal-based tool for monitoring the progress of data through a pipeline. It can be inserted into any normal pipeline between two processes to give a visual indication of how quickly data is passing through, how long it has taken, how near to completion it is, and an estimate of how long it will be until completion.

Invocation

Summary: pv [OPTION] [FILE]...

To use pv, insert it in a pipeline between two processes, with the appropriate options. Its standard input will be passed through to its standard output and progress will be shown on standard error.

pv will copy each supplied FILE in turn to standard output (- means standard input), or if no FILEs are specified just standard input is copied. This is the same behaviour as cat.

A simple example to watch how quickly a file is transferred using nc:

pv file | nc -w 1 somewhere.com 3000

A similar example, transferring a file from another process and passing the expected size to pv:

cat file | pv -s 12345 | nc -w 1 somewhere.com 3000

A more complicated example using numeric output to feed into the dialog program for a full-screen progress display:

(tar cf - . \
 | pv -n -s `du -sb . | awk '{print $1}'` \
 | gzip -9 > out.tgz) 2>&1 \
| dialog --gauge 'Progress' 7 70

Frequent use of this third form is not recommended as it may cause the programmer to overheat.

pv takes many options, which are divided into display switches, output modifiers, and general options.

Display switches

If no display switches are specified, pv behaves as if -p, -t, -e, -r, and -b had been given (i.e. everything is switched on). Otherwise, only those display types that are explicitly switched on will be shown.

-p
--progress: Turn the progress bar on. If standard input is not a file and no size was given (with the -s modifier), the progress bar cannot indicate how close to completion the transfer is, so it will just move left and right to indicate that data is moving.
-t
--timer: Turn the timer on. This will display the total elapsed time that pv has been running for.
-e
--eta: Turn the ETA timer on. This will attempt to guess, based on previous transfer rates and the total data size, how long it will be before completion. This option will have no effect if the total data size cannot be determined.
-r
--rate: Turn the rate counter on. This will display the current rate of data transfer.
-b
--bytes: Turn the total byte counter on. This will display the total amount of data transferred so far.
-n
--numeric: Numeric output. Instead of giving a visual indication of progress, pv will give an integer percentage, one per line, on standard error, suitable for piping (via convoluted redirection) into the dialog program. Note that -f is not required if -n is being used.
-q
--quiet: No output. Useful if the -L option is being used on its own to just limit the transfer rate of a pipe.

Output modifiers

-L RATE
--rate-limit RATE: Limit the transfer to a maximum of RATE bytes per second.
-W
--wait: Wait until the first byte has been transferred before showing any progress information or calculating any ETAs. Useful if the program you are piping to or from requires extra information before it starts, eg piping data into gpg or mcrypt which require a passphrase before data can be processed.
-s SIZE
--size SIZE: Assume the total amount of data to be transferred is SIZE bytes when calculating percentages and ETAs.
-i SEC
--interval SEC: Wait SEC seconds between updates. The default is to update every second.
-w WIDTH
--width WIDTH: Assume the terminal is WIDTH characters wide, instead of trying to work it out (or assuming 80 if it cannot be guessed).
-N NAME
--name NAME: Prefix the output information with NAME. Useful in conjunction with -c if you have a complicated pipeline and you want to be able to tell different parts of it apart.
-f
--force: Force output. Normally, pv will not output any visual display if standard error is not a terminal. This option forces it to do so.
-c
--cursor: Use cursor positioning escape sequences instead of just using carriage returns. This is useful in conjunction with -N (name) if you are using multiple pv invocations in a single, long, pipeline. However, it is likely to result in a garbled display if used near the bottom of the screen and should be considered slightly experimental.

General options

-h
--help: Print a usage message on standard output and exit successfully.
-l
--license: Print details of the program's license on standard output and exit successfully.
-V
--version: Print version information on standard output and exit successfully.