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pv

monitor the progress of data through a pipe

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

- Measure the speed and amount of data flow between pipes (`-s` is optional):
command1 | pv -s [expected_amount_of_data_for_eta] | command2

- Filter a file, see both progress and amount of output data:
pv -cN in [big_text_file] | grep [pattern] | pv -cN out > [filtered_file]

- Attach to an already running process and see its file reading progress:
pv -d [PID]

- Read an erroneous file, skip errors as `dd conv=sync,noerror` would:
pv -EE [path/to/faulty_media] > image.img

- Stop reading after reading specified amount of data, rate limit to 1K/s:
pv -L 1K -S [maximum_file_size_to_be_read]

pv [OPTION] [FILE]...
pv
[-h|-V]

pv allows a user to see the progress of data through a pipeline, by giving information such as time elapsed, percentage completed (with progress bar), current throughput rate, total data transferred, and ETA.

To use it, 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(1).

A simple example to watch how quickly a file is transferred using nc(1):

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(1) 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.

If no display switches are specified, pv behaves as if -p, -t, -e, -r, and -b had been given (i.e. everything except average rate 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.

-a, --average-rate

Turn the average rate counter on. This will display the average rate of data transfer so far.

-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 dialog(1). 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.

-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(1) or mcrypt(1) 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. The same suffixes of "k", "m" etc can be used as with -L.

-l, --line-mode

Instead of counting bytes, count lines (newline characters). The progress bar will only move when a new line is found, and the value passed to the -s option will be interpreted as a line count.

-i SEC, --interval SEC

Wait SEC seconds between updates. The default is to update every second. Note that this can be a decimal such as 0.1.

-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).

-H HEIGHT, --height HEIGHT

Assume the terminal is HEIGHT rows high, instead of trying to work it out (or assuming 25 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.

-L RATE, --rate-limit RATE

Limit the transfer to a maximum of RATE bytes per second. A suffix of "k", "m", "g", or "t" can be added to denote kilobytes (*1024), megabytes, and so on.

-B BYTES, --buffer-size BYTES

Use a transfer buffer size of BYTES bytes. A suffix of "k", "m", "g", or "t" can be added to denote kilobytes (*1024), megabytes, and so on. The default buffer size is the block size of the input file’s filesystem multiplied by 32 (512kb max), or 400kb if the block size cannot be determined.

-R PID, --remote PID

If PID is an instance of pv that is already running, -R PID will cause that instance to act as though it had been given this instance’s command line instead. For example, if pv -L 123k is running with process ID 9876, then running pv -R 9876 -L 321k will cause it to start using a rate limit of 321k instead of 123k. Note that some options cannot be changed while running, such as -c, -l, and -f.

-h, --help

Print a usage message on standard output and exit successfully.

-V, --version

Print version information on standard output and exit successfully.

An exit status of 1 indicates a problem with the -R option.

Any other exit status is a bitmask of the following:

2

One or more files could not be accessed, stat(2)ed, or opened.

4

An input file was the same as the output file.

8

Internal error with closing a file or moving to the next file.

16

There was an error while transferring data from one or more input files.

32

A signal was caught that caused an early exit.

64

Memory allocation failed.

A zero exit status indicates no problems.

Andrew Wood <andrew.wood@ivarch.com>
http://www.ivarch.com/

Kevin Coyner <kcoyner@debian.org>
(Debian package maintainer)

Jakub Hrozek <jhrozek@redhat.com>
(Fedora package maintainer)

Cedric Delfosse <cedric@debian.org>
(previous Debian package maintainer)

Eduardo Aguiar <eduardo.oliveira@sondabrasil.com.br>
(provided Portuguese [Brazilian] translation)

Stephane Lacasse <stephane@gorfou.ca>
(provided French translation)
http://gorfou.ca/

Marcos Kreinacke <public@kreinacke.com>
(provided German translation)

Bartosz Fenski <fenio@o2.pl>
(provided Polish translation, along with Krystian Zubel)
http://skawina.eu.org/

Joshua Jensen
(reported RPM installation bug)

Boris Folgmann
(reported cursor handling bug)
http://www.folgmann.com/en/

Mathias Gumz
(reported NLS bug)

Daniel Roethlisberger
(submitted patch to use lockfiles for -c if terminal locking fails)

Adam Buchbinder
(lots of help with a Cygwin port of -c)

Mark Tomich
(suggested -B option)
http://metuchen.dyndns.org

Gert Menke
(reported bug when piping to dd with a large input buffer size)

Ville Herva <Ville.Herva@iki.fi>
(informative bug report about rate limiting performance)

Elias Pipping
(patch to compile properly on Darwin 9; potential NULL deref report)

Patrick Collison
(similar patch for OS X)

Boris Lohner
(reported problem that -L does not complain if given non-numeric value)

Sebastian Kayser
(supplied testing for SIGPIPE, demonstrated internationalisation problem)

Laszlo Ersek
(reported shared memory leak on SIGINT with -c)
http://phptest11.atw.hu/

Phil Rutschman
(provided a patch for fully restoring terminal state on exit)
http://bandgap.rsnsoft.com/

Henry Precheur
(reporting and suggestions for --rate-limit bug when rate is under 10)
http://henry.precheur.org/

E. Rosten
(supplied patch for block buffering in line mode)
http://mi.eng.cam.ac.uk/~er258/

Kjetil Torgrim Homme
(reported compilation error with default CFLAGS on non-GCC compilers)

Alexandre de Verteuil
(reported bug in OS X build and supplied test environment to fix in)

Martin Baum
(supplied patch to return nonzero exit status if terminated by signal)

Sam Nelson
(supplied patch to fix trailing slash on DESTDIR)
http://www.siliconfuture.net/

Daniel Pape
(reported Cygwin installation problem due to DESTDIR)

Henry Gebhardt <hsggebhardt@googlemail.com>
(supplied patches to improve SI prefixes and add --average-rate)

Vladimir Kokarev
Alexander Leo
(reported that exit status did not reflect file errors)

If you find any bugs, please contact the primary author, either by email or by using the contact form on the web site.

cat(1), dialog(1)

This is free software, distributed under the ARTISTIC 2.0 license.

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e-mail: sschubert89@gmail.com

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