.TH @UCPACKAGE@ 1 "May 2014" Linux "User Manuals"
.SH NAME
@PACKAGE@ \- monitor the progress of data through a pipe
.SH SYNOPSIS
.B @PACKAGE@
[\fIOPTION\fR]
[\fIFILE\fR]...
.br
.B @PACKAGE@
[\fI\-h\fR|\fI\-V\fR]


.SH DESCRIPTION
.B @PACKAGE@
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.

.B @PACKAGE@
will copy each supplied
.B FILE
in turn to standard output
.BR "" "(" -
means standard input), or if no
.BR FILE s
are specified just standard input is copied. This is the same behaviour
as
.BR cat (1).

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

.RS
.B @PACKAGE@ file | nc -w 1 somewhere.com 3000
.RE

A similar example, transferring a file from another process and passing the
expected size to
.BR @PACKAGE@ :

.RS
.B cat file | @PACKAGE@ -s 12345 | nc -w 1 somewhere.com 3000
.RE

A more complicated example using numeric output to feed into the
.BR dialog (1)
program for a full-screen progress display:
 
.RS
.B (tar cf - . \e
.br
.B " | @PACKAGE@ -n -s $(du -sb . | awk '{print $1}') \e"
.br
.B " | gzip -9 > out.tgz) 2>&1 \e"
.br
.B | dialog --gauge 'Progress' 7 70
.RE

Taking an image of a disk, skipping errors:

.RS
.B @PACKAGE@ -EE /dev/sda > disk-image.img
.RE

Writing an image back to a disk:

.RS
.B @PACKAGE@ disk-image.img > /dev/sda
.RE

Zeroing a disk:

.RS
.B @PACKAGE@ < /dev/zero > /dev/sda
.RE

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
.B @PACKAGE@
will automatically stop at that size as if
.B \-S
had been given.

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

.RS
.B @PACKAGE@ -d 1234:3
.RE

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

.RS
.B @PACKAGE@ -d 1234
.RE


.SH OPTIONS
.B @PACKAGE@
takes many options, which are divided into display switches, output
modifiers, and general options.


.SH DISPLAY SWITCHES
If no display switches are specified,
.B @PACKAGE@
behaves as if
.BR \-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.
.TP
.B \-p, \-\-progress
Turn the progress bar on.  If standard input is not a file and no
size was given (with the
.B \-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.
.TP
.B \-t, \-\-timer
Turn the timer on.  This will display the total elapsed time that
.B @PACKAGE@
has been running for.
.TP
.B \-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.
.TP
.B \-r, \-\-rate
Turn the rate counter on.  This will display the current rate of data
transfer.
.TP
.B \-a, \-\-average\-rate
Turn the average rate counter on.  This will display the average rate of
data transfer so far.
.TP
.B \-b, \-\-bytes
Turn the total byte counter on.  This will display the total amount of
data transferred so far.
.TP
.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
.B %T
in the
.B FORMATTING
section below.
.TP
.B \-A, \-\-last\-written NUM
Show the last
.B NUM
bytes written - but see the caveat under
.B %nA
in the
.B FORMATTING
section below.
.TP
.B \-F, \-\-format FORMAT
Ignore the options
.BR \-p ,
.BR \-t ,
.BR \-e ,
.BR \-r ,
.BR \-a ,
.BR \-b ,
.BR \-T ,
and
.BR \-A ,
and instead use the format string
.B FORMAT
to determine the output format.  See the
.B FORMATTING
section below.
.TP
.B \-n, \-\-numeric
Numeric output.  Instead of giving a visual indication of progress,
.B @PACKAGE@
will give an integer percentage, one per line, on standard error, suitable
for piping (via convoluted redirection) into
.BR dialog (1).
Note that
.B \-f
is not required if
.B \-n
is being used.
.TP
.B ""
Note that if
.B \-\-numeric
is in use, then adding
.B \-\-bytes
will cause the number of bytes processed so far to be output instead of a
percentage; if
.B \-\-line\-mode
is also in use, then instead of bytes or a percentage, the number of lines
so far is output.  And finally, if
.B \-\-timer
is also in use, then each output line is prefixed with the elapsed time 
so far, as a decimal number of seconds.
.TP
.B \-q, \-\-quiet
No output.  Useful if the
.B \-L
option is being used on its own to just limit the transfer rate of a pipe.


.SH OUTPUT MODIFIERS
.TP
.B \-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
.BR gpg (1)
or
.BR mcrypt (1)
which require a passphrase before data can be processed.
.TP
.B \-s SIZE, \-\-size SIZE
Assume the total amount of data to be transferred is
.B SIZE
bytes when calculating percentages and ETAs.  The same suffixes of "k", "m"
etc can be used as with
.BR -L .
.TP
.B ""
Has no effect if used with
.B -d PID
to watch all file descriptors of a process, but will work with
.BR "-d PID:FD" .
.TP
.B \-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
.B \-s
option will be interpreted as a line count.
.TP
.B \-0, \-\-null
Count lines as null terminated.  This option implies \-\-line\-mode.
.TP
.B \-i SEC, \-\-interval SEC
Wait
.B SEC
seconds between updates.  The default is to update every second.
Note that this can be a decimal such as 0.1.
.TP
.B \-w WIDTH, \-\-width WIDTH
Assume the terminal is
.B WIDTH
characters wide, instead of trying to work it out (or assuming 80 if it
cannot be guessed).
.TP
.B \-H HEIGHT, \-\-height HEIGHT
Assume the terminal is
.B HEIGHT
rows high, instead of trying to work it out (or assuming 25 if it
cannot be guessed).
.TP
.B \-N NAME, \-\-name NAME
Prefix the output information with
.BR NAME .
Useful in conjunction with
.B \-c
if you have a complicated pipeline and you want to be able to tell different
parts of it apart.
.TP
.B \-f, \-\-force
Force output.  Normally,
.B @PACKAGE@
will not output any visual display if standard error is not a terminal. 
This option forces it to do so.
.TP
.B \-c, \-\-cursor
Use cursor positioning escape sequences instead of just using carriage
returns.  This is useful in conjunction with
.B \-N
(name) if you are using multiple
.B @PACKAGE@
invocations in a single, long, pipeline.


.SH DATA TRANSFER MODIFIERS
.TP
.B \-L RATE, \-\-rate-limit RATE
Limit the transfer to a maximum of
.B RATE
bytes per second.  A suffix of "k", "m", "g", or "t" can be added to denote
kilobytes (*1024), megabytes, and so on.
.TP
.B \-B BYTES, \-\-buffer-size BYTES
Use a transfer buffer size of
.B 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.
.TP
.B \-C, \-\-no-splice
Never use
.BR splice (2),
even if it would normally be possible.  The
.BR splice (2)
system call is a more efficient way of transferring data from or to a pipe
than regular
.BR read (2)
and
.BR write (2),
but means that the transfer buffer may not be used.  This prevents
.B \-A
and
.B \-T
from working, so if you want to use
.B \-A
or
.B \-T
then you will need to use
.BR \-C ,
at the cost of a small loss in transfer efficiency.
(This option has no effect on systems where
.BR splice (2)
is unavailable).
.TP
.B \-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
.B dd conv=sync,noerror
but has not been as thoroughly tested.
.TP
.B ""
Specify
.B \-E
twice to only report a read error once per file, instead of reporting each
byte range skipped.
.TP
.B \-S, \-\-stop-at-size
If a size was specified with
.BR \-s ,
stop transferring data once that many bytes have been written, instead of
continuing to the end of input.
.TP
.B \-d PID[:FD], \-\-watchfd PID[:FD]
Instead of transferring data, watch file descriptor
.B FD
of process
.BR PID ,
and show its progress.  The
.B @PACKAGE@
process will exit when
.B 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.
.TP
.B ""
If only a
.B 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
.B @PACKAGE@
process will exit when process
.B PID
exits.
.TP
.B \-R PID, \-\-remote PID
If
.B PID
is an instance of
.B @PACKAGE@
that is already running,
.B \-R PID
will cause that instance to act as though it had been given
this instance's command line instead.  For example, if
.B @PACKAGE@ -L 123k
is running with process ID 9876, then running
.B @PACKAGE@ -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
.BR \-c ,
.BR \-l ,
.BR \-f ,
.BR \-E ,
and
.BR \-S .

.SH GENERAL OPTIONS
.TP
.B \-P FILE, \-\-pidfile FILE
Save the process ID of
.B @PACKAGE@
in
.BR FILE .
The file will be truncated if it already exists, and will be removed when
.B @PACKAGE@
exits.  While
.B @PACKAGE@
is running, it will contain a single number - the process ID of
.B @PACKAGE@
- followed by a newline.
.TP
.B \-h, \-\-help
Print a usage message on standard output and exit successfully.
.TP
.B \-V, \-\-version         
Print version information on standard output and exit successfully.


.SH FORMATTING
If the
.B \-F
option is given, then the output format is determined by the given format
string.  Within that string, the following sequences can be used:
.TP
.B %p
Progress bar.
Expands to fill the remaining space. Should only be specified once.
Equivalent to
.BR \-p .
.TP
.B %t
Elapsed time.  Equivalent to
.BR \-t .
.TP
.B %e
ETA.  Equivalent to
.BR \-e .
.TP
.B %r
Current data transfer rate.  Equivalent to
.BR \-r .
.TP
.B %a
Average data transfer rate.  Equivalent to
.BR \-a .
.TP
.B %b
Bytes transferred so far (or lines if
.B \-l
was specified).  Equivalent to
.BR \-b .
.TP
.B %T
Percentage of the transfer buffer in use.  Equivalent to
.BR \-T .
Shows "{----}" if the transfer is being done with
.BR splice (2),
since splicing to or from pipes does not use the buffer.
.TP
.B %nA
Show the last 
.B n
bytes written (e.g.
.B %16A
for the last 16 bytes).
Shows only dots if the transfer is being done with
.BR splice (2),
since splicing to or from pipes does not use the buffer.
.TP
.B %N
Name prefix given by
.BR -N .
Padded to 9 characters with spaces, and suffixed with :.
.TP
.B %%
A single %.
.P
The format string equivalent of turning on all display switches is
.BR "\`%N %b %T %t %r %a %p %e'" .


.SH EXIT STATUS
An exit status of 1 indicates a problem with the
.B \-R
or
.B \-P
options.

Any other exit status is a bitmask of the following:

.TP
.B 2
One or more files could not be accessed, 
.BR stat (2)ed,
or opened.
.TP
.B 4
An input file was the same as the output file.
.TP
.B 8
Internal error with closing a file or moving to the next file.
.TP
.B 16
There was an error while transferring data from one or more input files.
.TP
.B 32
A signal was caught that caused an early exit.
.TP
.B 64
Memory allocation failed.

A zero exit status indicates no problems.


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


.SH KNOWN PROBLEMS
The following problems are known to exist in
.BR @PACKAGE@ :
.TP
.B *
The
.B -c
option does not work properly on Cygwin without
.B cygserver
running, if started near the bottom of the screen (IPC is needed to handle
the terminal scrolling).  To fix this, start
.B cygserver
before using
.BR "@PACKAGE@ -c" .
.P
.TP
.B *
The
.B -R
option is not available on Cygwin without
.B cygserver
running (SYSV IPC is needed). To fix this, start
.B cygserver
before running the instance of
.B @PACKAGE@
you want, at runtime, to change the parameters of.
.P
If you find any other problems, please report them.


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


.SH "SEE ALSO"
.BR cat (1),
.BR dialog (1),
.BR splice (2)


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