pv(1) — Linux manual page


PV(1)                         User Manuals                         PV(1)

NAME         top

       pv - monitor the progress of data through a pipe

SYNOPSIS         top

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

DESCRIPTION         top

       pv shows 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

              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

       Taking an image of a disk, skipping errors:

              pv -EE /dev/your/disk/device > disk-image.img

       Writing an image back to a disk:

              pv disk-image.img > /dev/your/disk/device

       Zeroing a disk:

              pv < /dev/zero > /dev/your/disk/device

       Note that if the input size cannot be calculated, and the output
       is a block device, then the size of the block device will be used
       and pv will automatically stop at that size as if -S had been

       (Linux only): Watching file descriptor 3 opened by another
       process 1234:

              pv -d 1234:3

       (Linux only): Watching all file descriptors used by process 1234:

              pv -d 1234

OPTIONS         top

       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 any inputs are not files, or
              are unreadable, and no size was explicitly 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 current 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.

       -I, --fineta
              Turn the ETA timer on, but display the estimated local
              time of arrival instead of time left.  When the estimated
              time is more than 6 hours in the future, the date is shown
              as well.

       -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
              current average rate of data transfer (default: last 30s,
              see -m).

       -b, --bytes
              Turn the total byte counter on.  This will display the
              total amount of data transferred so far.

       -8, --bits
              Display the total bits instead of the total bytes.  The
              output suffix will be "b" instead of "B".

       -T, --buffer-percent
              Turn on the transfer buffer percentage display.  This will
              show the percentage of the transfer buffer in use - but
              see the caveat under %T in the FORMATTING section below.
              Implies -C.

       -A NUM, --last-written NUM
              Show the last NUM bytes written - but see the caveat under
              %nA in the FORMATTING section below.  Implies -C.

       -F FORMAT, --format FORMAT
              Ignore the options -p, -t, -e, -r, -a, -b, -T, and -A, and
              instead use the format string FORMAT to determine the
              output format.  See the FORMATTING section below.

       -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.

              Note that if --numeric is in use, then adding --bytes will
              cause the number of bytes processed so far to be output
              instead of a percentage; if --line-mode is also in use as
              well as --bytes and --numeric, then instead of bytes or a
              percentage, the number of lines so far is output.  And
              finally, if --timer is added to --numeric, then each
              output line is prefixed with the elapsed time so far, as a
              decimal number of seconds.

       -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.

       -D SEC, --delay-start SEC
              Wait until SEC seconds have passed before showing any
              progress information, for example in a script where you
              only want to show a progress bar if it starts taking a
              long time.  Note that this can be a decimal such as 0.5.

       -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.

              If SIZE starts with @, the size of file whose name follows
              the @ will be used.

              Note that --size has no effect if used with -d PID to
              watch all file descriptors of a process, but will work
              with -d PID:FD.

       -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.

              If this option is used without -s, the "total size" (in
              this case, total line count) is calculated by reading
              through all input files once before transfer starts.  If
              any inputs are pipes or non-regular files, or are
              unreadable, the total size will not be calculated.

       -0, --null
              Count lines as terminated with a zero byte instead of with
              a newline.  This option implies --line-mode.

       -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.

       -m SEC, --average-rate-window SEC
              Compute current average rate over a SEC seconds window for
              average rate and ETA calculations (default 30 seconds).

       -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).  If this option is used, the output width will
              not be adjusted if the width of the terminal changes while
              the transfer is running.

       -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).
              If this option is used, the output height will not be
              adjusted if the height of the terminal changes while the
              transfer is running.

       -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
              kibibytes (*1024), mebibytes, 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 kibibytes
              (*1024), mebibytes, and so on.  The default buffer size is
              the block size of the input file's filesystem multiplied
              by 32 (512KiB max), or 400KiB if the block size cannot be
              determined.  This can be useful on platforms like MacOS
              which perform better in pipelines with specific buffer
              sizes such as 1024.  Implies -C.

       -C, --no-splice
              Never use splice(2), even if it would normally be
              possible.  The splice(2) system call is a more efficient
              way of transferring data from or to a pipe than regular
              read(2) and write(2), but means that the transfer buffer
              may not be used.  This prevents -A and -T from working,
              cannot work with -X, and makes -B redundant, so using -A,
              -T, -X, or -B automatically switches on -C.  Switching on
              -C results in a small loss of transfer efficiency.  (This
              option has no effect on systems where splice(2) is

       -E, --skip-errors
              Ignore read errors by attempting to skip past the
              offending sections.  The corresponding parts of the output
              will be null bytes.  At first only a few bytes will be
              skipped, but if there are many errors in a row then the
              skips will move up to chunks of 512.  This is intended to
              be similar to dd conv=sync,noerror but has not been as
              thoroughly tested.

              Specify -E twice to only report a read error once per
              file, instead of reporting each byte range skipped.

       -Z BYTES, --error-skip-block BYTES
              When ignoring read errors with -E, instead of trying to
              adaptively skip by reading small amounts and skipping
              progressively larger sections until a read succeeds, move
              to the next file block of BYTES bytes as soon as an error
              occurs.  There may still be some shorter skips where the
              block being skipped coincides with the end of the transfer

              This option can only be used with -E and is intended for
              use when reading from a block device, such as -E -Z 4K to
              skip in 4 kibibyte blocks.  This will speed up reads from
              faulty media, at the expense of potentially losing more

       -S, --stop-at-size
              If a size was specified with -s, stop transferring data
              once that many bytes have been written, instead of
              continuing to the end of input.

       -Y, --sync
              After every write operation, synchronise the buffer caches
              to disk - see fdatasync(2).  This has no effect when the
              output is a pipe.  Using -Y may improve the accuracy of
              the progress bar when writing to a slow disk.

       -K, --direct-io
              Set the O_DIRECT flag on all inputs and outputs, if it is
              available.  This will minimise the effect of caches, at
              the cost of performance.  Due to memory alignment
              requirements, it also may cause read or write failures
              with an error of "Invalid argument", especially if reading
              and writing files across a variety of filesystems in a
              single pv call.  Use this option with caution.

       -X, --discard
              Instead of transferring input data to standard output,
              discard it.  This is equivalent to redirecting standard
              output to /dev/null, except that write(2) is never called.
              Implies -C.

       -d PID[:FD], --watchfd PID[:FD]
              Instead of transferring data, watch file descriptor FD of
              process PID, and show its progress.  The pv process will
              exit when FD either changes to a different file, changes
              read/write mode, or is closed; other data transfer
              modifiers - and remote control - may not be used with this

              If only a PID is specified, then that process will be
              watched, and all regular files and block devices it opens
              will be shown with a progress bar.  The pv process will
              exit when process PID exits.

       -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 321KiB instead of 123KiB.  Note that
              some options cannot be changed while running, such as -c,
              -l, -f, -D, -E, and -S.


       -P FILE, --pidfile FILE
              Save the process ID of pv in FILE.  The file will be
              replaced if it already exists, and will be removed when pv
              exits.  While pv is running, it will contain a single
              number - the process ID of pv - followed by a newline.

       -h, --help
              Print a usage message on standard output and exit

       -V, --version
              Print version information on standard output and exit

FORMATTING         top

       If the -F option is given, then the output format is determined
       by the given format string.  Within that string, the following
       sequences can be used:

       %p     Progress bar.  Expands to fill the remaining space. Should
              only be specified once.  Equivalent to -p.

       %t     Elapsed time.  Equivalent to -t.

       %e     ETA as time remaining.  Equivalent to -e.

       %I     ETA as local time of completion.  Equivalent to -I.

       %r     Current data transfer rate.  Equivalent to -r.

       %a     Average data transfer rate.  Equivalent to -a.

       %b     Bytes transferred so far (or lines if -l was specified).
              Equivalent to -b.  If --bits was specified, %b shows the
              bits transferred so far, not bytes.

       %T     Percentage of the transfer buffer in use.  Equivalent to
              -T.  Shows "{----}" if the transfer is being done with
              splice(2), since splicing to or from pipes does not use
              the buffer.

       %nA    Show the last n bytes written (e.g.  %16A for the last 16
              bytes).  Shows only dots if the transfer is being done
              with splice(2), since splicing to or from pipes does not
              use the buffer.

       %N     Name prefix given by -N.  Padded to 9 characters with
              spaces, and suffixed with :.

       %%     A single %.

       The format string equivalent of turning on all display switches
       is `%N %b %T %t %r %a %p %e'.


       Some suggested common switch combinations:

       pv -ptebar
              Show a progress bar, elapsed time, estimated completion
              time, byte counter, average rate, and current rate.

       pv -betlap
              Show a progress bar, elapsed time, estimated completion
              time, line counter, and average rate, counting lines
              instead of bytes.

       pv -t  Show only the elapsed time - useful as a simple timer,
              e.g.  sleep 10m | pv -t.

       pv -pterb
              The default behaviour: progress bar, elapsed time,
              estimated completion time, current rate, and byte counter.

       On MacOS, it may be useful to specify -B 1024 in a pipeline, as
       this may improve performance.

EXIT STATUS         top

       An exit status of 1 indicates a problem with the -R or -P

       Any other exit status is a bitmask of the following:

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

       4      An input file was the same as the output file.

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

       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.

AUTHOR         top

       Written by Andrew Wood, with patches submitted by various other
       people.  Please see the package's ACKNOWLEDGEMENTS file for a
       complete list of contributors.

KNOWN PROBLEMS         top

       The following problems are known to exist in pv:

       •  In some versions of bash(1) and zsh(1), the construct <(pv
          filename) will not output any progress to the terminal when
          run from an interactive shell, due to the subprocess being run
          in a separate process group from the one that owns the
          terminal.  In these cases, use --force.

       •  The -c option does not work properly on Cygwin without
          cygserver running, if started near the bottom of the screen
          (IPC is needed to handle the terminal scrolling).  To fix
          this, start cygserver before using pv -c.

       •  The -R option requires that either /run/user/<uid>/ or $HOME/
          can be written to, for inter-process communication.

       If you find any other problems, please report them.

REPORTING BUGS         top

       Please report any bugs to pv@ivarch.com.

       Alternatively, use the issue tracker linked from the pv home
       page: <https://www.ivarch.com/programs/pv.shtml>

SEE ALSO         top

       cat(1), dialog(1), splice(2), open(2) (for O_DIRECT)

COPYRIGHT         top

       Copyright © 2002-2008, 2010, 2012-2015, 2017, 2021, 2023 Andrew

       License GPLv3+: GNU GPL version 3 or later

       This is free software: you are free to change and redistribute
       it.  There is NO WARRANTY, to the extent permitted by law.

COLOPHON         top

       This page is part of the pv (Pipe Viewer) project.  Information
       about the project can be found at 
       ⟨http://www.ivarch.com/programs/pv.shtml⟩.  If you have a bug
       report for this manual page, see
       ⟨http://www.ivarch.com/programs/pv.shtml⟩.  This page was
       obtained from the tarball pv-1.8.5.tar.gz fetched from
       ⟨http://www.ivarch.com/programs/pv.shtml⟩ on 2023-12-22.  If you
       discover any rendering problems in this HTML version of the page,
       or you believe there is a better or more up-to-date source for
       the page, or you have corrections or improvements to the
       information in this COLOPHON (which is not part of the original
       manual page), send a mail to man-pages@man7.org

Linux                         November 2023                        PV(1)