PV(1) User Commands PV(1)

NAME

pv - monitor the progress of data through a pipe

SYNOPSIS

pv [OPTION]... [FILE]...

pv -d|--watchfd PID[:FD] [OPTION]...

pv -R|--remote PID [OPTION]...

DESCRIPTION

Show 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.

Each FILE is copied to standard output. With no FILE, or when FILE
is "-", standard input is read. This is the same behaviour as
cat(1).

OPTIONS

Display switches

If no display switches are specified, pv behaves as if "--progress",
"--timer", "--eta", "--rate", and "--bytes" had been given.
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 "--size",
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 - or, with "--gauge", the bar will
indicate the current rate as a percentage of the maximum rate
seen so far.

-t, --timer
Turn the timer on. This will display the total elapsed time
that pv has been running for.

-e, --eta
Turn the ETA countdown on. This will estimate, based on
current transfer rates and the total data size, how long it
will be before completion. The countdown is prefixed with
"ETA". This option will have no effect if the total data size
cannot be determined.

-I, --fineta
Turn the ETA countdown on, but display the estimated local
time at which the transfer will finish, instead of the amount
of time remaining. When the estimated time is more than 6
hours in the future, the date is shown as well. The time is
prefixed with "FIN" for finish time. As with "--eta", 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. The rate is shown in square brackets "[]".

-a, --average-rate
Turn the average rate counter on. This will display the
current average rate of data transfer, over the last 30
seconds by default (see "--average-rate-window"). The average
rate is shown in brackets "()".

-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. Implies
"--no-splice". The transfer buffer percentage is shown in
curly brackets "{}".

-A NUM, --last-written NUM
Show the last NUM bytes written. Implies "--no-splice".

-F FORMAT, --format FORMAT
Ignore all of the above options 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, write an integer percentage, one per line, on
standard error, suitable for passing to a tool such as
dialog(1). Note that "--force" is not required if "--numeric"
is being used.

Combining "--numeric" with "--bytes" will cause the number of
bytes processed so far to be output instead of a percentage.
Adding "--line-mode" as well as "--bytes" writes the number of
lines instead of bytes or a percentage. Adding "--rate" adds
the transfer rate to each output line (if "--bytes" is also in
use, the rate comes after the byte/line count). Adding
"--timer" prefixes each output line with the elapsed time so
far, as a decimal number of seconds.

Combining "--numeric" with "--format" allows for custom
output. The default format string components for "--numeric"
are "%t %b %r %{progress-amount-only}" in that order, each
item being active or inactive according to the rules above (so
the default with no other options is
"%{progress-amount-only}".

-q, --quiet
No output. Useful if the "--rate-limit" option is being used
on its own to limit the transfer rate of a pipe.

Output modifiers

-8, --bits
Use bits instead of bytes for the byte and rate counters. The
output suffix will be "b" instead of "B".

-k, --si
Display and interpret suffixes as multiples of 1000 rather
than the default of 1024. Note that this only takes effect on
options after this one, so for consistency, specify this
option first.

-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, such as when 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. The
value of SEC 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. A suffix of "K",
"M", "G", or "T" can be added to denote kibibytes (*1024),
mebibytes, gibibytes, tebibytes. If "--si" appears before
this option, suffixes will denote kilobytes (*1000),
megabytes, and so on instead.

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

-g, --gauge
If the progress bar is shown but the size is not known, then
instead of moving the bar left and right to show progress,
show the current transfer rate as a percentage of the maximum
rate seen so far.

-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 "--size" will be interpreted as a line
count.

If this option is used without "--size", 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 null 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. The value of SEC 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. The default is 30 seconds.
The value must be an integer.

-w WIDTH, --width WIDTH
Assume the terminal is WIDTH columns 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 "--cursor" if you have a complicated pipeline
and you want to be able to tell different parts of it apart.

-u STYLE, --bar-style STYLE
Change the default progress bar style shown by "--progress",
or by the "--format" sequences "%{progress}" or
"%{progress-bar-only}", to STYLE. The STYLE can be one of
plain (the default), block, granular, or shaded. These styles
are described in the FORMATTING section below.

-x SPEC, --extra-display SPEC
As well as displaying progress to the terminal, also write it
to SPEC. The SPEC must start with a comma-separated list of
destinations, and can optionally be followed by a colon and a
format string. The destinations can be windowtitle or window
for the xterm window title, and processtitle, proctitle,
process, or proc for the process title displayed by ps(1). If
a format string is not supplied, the same format is used as
for the terminal. For example, "-x 'window,process:%t %b %r'"
will show the elapsed time, bytes transferred, and rate, in
both the window title and the process title.

-v, --stats
At the end of the transfer, write an additional line showing
the transfer rate minimum, maximum, mean, and standard
deviation. The values are always in bytes per second (or
bits, with "--bits").

-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 "--name"
if you are using multiple pv invocations in a single pipeline.

Data transfer modifiers

-o FILE, --output FILE
Write data to FILE instead of standard output. If the file
already exists, it will be truncated.

-L RATE, --rate-limit RATE
Limit the transfer to a maximum of RATE bytes per second. The
same suffixes as "--size" can be used.

-B BYTES, --buffer-size BYTES
Use a transfer buffer size of BYTES bytes. The same suffixes
as "--size" can be used. 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 with pipelines that
perform better with specific buffer sizes such as 1024.
Implies "--no-splice".

-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 "--buffer-percent" and "--last-written" from
working, cannot work with "--discard", and makes
"--buffer-size" redundant, so using any of those options
automatically switches on "--no-splice". Switching on this
option results in a small loss of transfer efficiency. It 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".

Specify "--skip-errors" 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 "--skip-errors", 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 buffer.
The same suffixes as "--size" can be used.

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

-S, --stop-at-size
If a size was specified with "--size", 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 with fdatasync(2). This has no effect when the output is
a pipe. Using "--sync" 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
"--no-splice".

-U FILE, --store-and-forward FILE
Instead of passing data through immediately, do it in two
stages - first read all input and write it to FILE, and then
once the input is exhausted, read all of FILE and write it to
the output. FILE remains in place afterwards, unless it is
"-", in which case pv creates a temporary file for this
purpose, and automatically removes it afterwards.

This can be useful if you have a pipeline which generates data
(your input) quickly but you don't know the size, and you wish
to pass it to some slower process, once all of the input has
been generated and you know its size, so you can see its
progress. Note that when doing this with relatively small
amounts of data, "--no-splice" may be preferable so that pipe
buffering doesn't affect the progress display.

Alternative operating modes

-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
Remotely control another instance of pv with process ID PID,
making it act as though it had been given this instance's
command line. For example, if "pv --rate-limit 123K" is
running with process ID 9876, then running
"pv --remote 9876 --rate-limit 321K" will cause process 9876
to start using a rate limit of 321KiB instead of 123KiB. Note
that some options cannot be changed while running, such as
"--cursor", "--line-mode", "--force", "--delay-start",
"--skip-errors", and "--stop-at-size".

Other options

-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, FILE 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
successfully.

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

FORMATTING

Format strings used by "--format" and "--extra-display" can contain
the following sequences:

%p, %{progress}
Progress bar (suffixed with a percentage if the size is
known). Equivalent to "--progress". Expands to fill the
remaining space unless prefixed by a number to set the width,
such as "%20p" or "%20{progress}".

%{progress-bar-only}
Progress bar, without any sides, and without any percentage
displayed afterwards. Expands to fill the remaining space
unless prefixed by a number.

%{progress-amount-only}
The percentage completion (or maximum rate, with "--gauge"
when the size is unknown).

%{bar-plain}
Progress bar in the standard plain format, without any sides,
and without any percentage displayed afterwards. Expands to
fill the remaining space unless prefixed by a number.

%{bar-block}
Progress bar using Unicode full blocks, without any sides, and
without any percentage displayed afterwards. Expands to fill
the remaining space unless prefixed by a number. If UTF-8
output is not available, the plain format is used.

%{bar-granular}
Progress bar using Unicode full blocks, and 1/8th blocks for
partial fills, providing a more granular display. Like the
other "%{bar}" strings this shows the bar without any sides,
and without any percentage displayed afterwards, and expands
to fill the remaining space unless prefixed by a number. If
UTF-8 output is not available, the plain format is used.

%{bar-shaded}
Progress bar using Unicode full blocks and shade characters -
dark and medium shade are used for partial fills, and the
light shade is used for the background. Like the other
"%{bar}" strings this shows the bar without any sides, and
without any percentage displayed afterwards, and expands to
fill the remaining space unless prefixed by a number. If
UTF-8 output is not available, the plain format is used.

%t, %{timer}
Elapsed time. Equivalent to "--timer".

%e, %{eta}
ETA as time remaining. Equivalent to "--eta".

%I, %{fineta}
ETA as local time at which the transfer will finish.
Equivalent to "--fineta".

%r, %{rate}
Current data transfer rate. Equivalent to "--rate".

%a, %{average-rate}
Average data transfer rate. Equivalent to "--average-rate".

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

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

%nA, %n{last-written}
Show the last n bytes written (for example, "%16A" shows 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.

%nL, %n{previous-line}
Show the first n bytes of the most recently written line (for
example, "%40L" shows the first 40 bytes). If no n is given,
then this expands to fill the available space. Shows only
spaces if the transfer is being done with splice(2).

%N, %{name}
Show the name prefix given by "--name". Padded to 9
characters with spaces, and suffixed with ":".

%{sgr:colour,...}
Emit ECMA-48 SGR (Select Graphic Rendition) codes if the
terminal supports colours, where colour,... is a comma-
separated list of any of the keywords below, or the numeric
values from console_codes(4). If colour support is not
available, nothing is emitted.

Supported keywords are: reset or none, black, red, green,
brown or yellow, blue, magenta, cyan, white, fg-black, fg-red,
fg-green, fg-brown or fg-yellow, fg-blue, fg-magenta, fg-cyan,
fg-white, fg-default, bg-black, bg-red, bg-green, bg-brown or
bg-yellow, bg-blue, bg-magenta, bg-cyan, bg-white, bg-default,
bold, dim, italic, underscore or underline, blink, reverse,
no-bold or no-dim, no-italic, no-underscore or no-underline,
no-blink, no-reverse.

With colours, the optional "fg-" prefix indicates foreground;
a prefix of "bg-" indicates background.

For example, "%{sgr:green,bold}TEXT%{sgr:reset}" will make
TEXT bold green on supported terminals.

%% A single "%".

Any other contents are reproduced in the progress display as-is.

The format string equivalent of the default display switches is
"%b %t %r %p %e".

EXAMPLES

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 -btrpg
Show the amount transferred, elapsed time, current rate, and a
gauge showing the current rate as a percentage of the maximum
rate seen - useful in a pipeline where the total size is
unknown. (If the size is known, these options will show the
percentage completion instead of the rate gauge).

pv -t Show only the elapsed time - useful as a simple timer, such as
"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 "--buffer-size 1024" in a
pipeline, as this may improve performance.

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 --size 12345 | nc -w 1 somewhere.com 3000

To watch the progress of creating a tar.gz archive:

tar cf - directory/ \
| pv --size $(du -sb directory/ | awk '{print $1}') \
| gzip -9 \
> out.tar.gz

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 "--stop-at-size" had been
given.

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

pv --watchfd 1234:3

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

pv --watchfd 1234

Rate-limiting the transfer between two processes in a pipeline, with
no display:

producer | pv --quiet --rate-limit 1M | consumer

Sending logs to a processing script, showing the most recent line as
part of the progress display:

pv --format '%a %p : %L' big.log | processing-script

Showing progress as lines of JSON data:

pv --numeric --format '{"elapsed":%t,"bytes":%b,"rate":%r,"percentage":%{progress-amount-only}}' big.log | processing-script

EXIT STATUS

An exit status of 1 indicates a problem with the "--remote" or
"--pidfile" 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.

ENVIRONMENT

The following environment variables may affect pv:

HOME The current user's home directory. This may be used by
"--remote" to exchange messages between pv instances: if the
/run/user/UID/ directory does not exist (where UID is the
current user ID), then $HOME/.pv/ will be used instead.

TMPDIR, TMP
The directory to create per-tty lock files for the terminal
when using "--cursor". If TMPDIR is set to a non-empty value,
it is the directory under which lock files are created.
Otherwise, TMP is used. If neither are set, then /tmp is
used.

NOTES

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".

If pv is used in a pipeline in zsh version 5.8, and the last command
in the pipeline is based on shell builtins, zsh takes control of the
terminal away from pv, preventing progress from being displayed. For
example, this will produce no progress bar:

pv InputFile | { while read -r line; do sleep 0.1; done; }

To work around this, put the last commands of the pipeline in normal
brackets to force the use of a subshell:

pv InputFile | ( while read -r line; do sleep 0.1; done; )

Refer to issue #105 <https://codeberg.org/a-j-wood/pv/issues/105> for
full details.

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

The "--size" option has no effect if used with "--watchfd PID" to
watch all file descriptors of a process, but will work with
"--watchfd PID:FD" to watch a single file descriptor.

If the input size cannot be calculated, and the output is a block
device, then pv will read the output device's size, use that as if it
had been passed to "--size", and activate "--stop-at-size".

The "%nA" and "%nL" format sequences may not be effective with small
input files, and "%nL" may be a few lines out due to buffering within
the pipeline itself.

Numbers passed to "--size", "--rate-limit", "--buffer-size", and
"--error-skip-block" may all be expressed as decimals if followed by
a suffix, so for example "--size 1.5G" is equivalent to
"--size 1536M".

Numbers passed to "--interval" and "--delay-start" may be integers or
decimals, but may not have a suffix.

Numbers passed to "--last-written", "--width", "--height",
"--average-rate-window", and "--remote" must be integers with no
suffix.

REPORTING BUGS

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

cat(1), splice(2), fdatasync(2), open(2) (for O_DIRECT),
console_codes(4)

COPYRIGHT

Copyright (C) 2002-2008, 2010, 2012-2015, 2017, 2021, 2023-2025
Andrew Wood.

License GPLv3+: GNU GPL version 3 or later
<https://www.gnu.org/licenses/gpl-3.0.html>.

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

Please see the package's ACKNOWLEDGEMENTS file for a complete list of
contributors.

pv-1.9.31 2025-01-28 PV(1)