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/sda > disk-image.img

       Writing an image back to a disk:

              pv disk-image.img > /dev/sda

       Zeroing a disk:

              pv < /dev/zero > /dev/sda

       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 given.

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

              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 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.

       -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
              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.

       -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.

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

       -F, --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, then
              instead of bytes or a percentage, the number of lines so far
              is output.  And finally, if --timer is also in use, 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

       -D, --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.

              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.  Note that file sizes are not automatically
              calculated when this option is used, to avoid having to read
              all files twice.

       -0, --null
              Count lines as null terminated.  This option implies

       -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

       -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
              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.

       -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, so if you want to use -A
              or -T then you will need to use -C, at the cost of a small
              loss in transfer efficiency.  (This option has no effect on
              systems where splice(2) is unavailable).

       -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.

       -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.

       -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 option.

              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 truncated
              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.

       %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

       %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

       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.

EXIT STATUS         top

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

       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.

AUTHOR         top

       Written by Andrew Wood, with patches submitted by various other
       people.  Please see the package README for a complete list of

KNOWN PROBLEMS         top

       The following problems are known to exist in pv:

       *      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 is not available on Cygwin without cygserver
              running (SYSV IPC is needed). To fix this, start cygserver
              before running the instance of pv you want, at runtime, to
              change the parameters of.

       If you find any other problems, please report them.

REPORTING BUGS         top

       Report bugs in pv to pv@ivarch.com or use the contact form linked
       from the pv home page: <http://www.ivarch.com/programs/pv.shtml>

SEE ALSO         top

       cat(1), dialog(1), splice(2)

LICENSE         top

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

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-1.6.6.tar.bz2 fetched from
       ⟨http://www.ivarch.com/programs/pv.shtml⟩ on 2020-11-01.  If you dis‐
       cover 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                             June 2017                            PV(1)