1PV(1) User Manuals PV(1)
2
6 pv - monitor the progress of data through a pipe
7
9 pv [OPTION] [FILE]...
10 pv [-h|-V]
11
15 pv shows the progress of data through a pipeline by giving information
16 such as time elapsed, percentage completed (with progress bar), current
17 throughput rate, total data transferred, and ETA.
18 To use it, insert it in a pipeline between two processes, with the ap‐
20 propriate options. Its standard input will be passed through to its
21 standard output and progress will be shown on standard error.
22 pv will copy each supplied FILE in turn to standard output (- means
24 standard input), or if no FILEs are specified just standard input is
25 copied. This is the same behaviour as cat(1).
26 A simple example to watch how quickly a file is transferred using
28 nc(1):
29 pv file | nc -w 1 somewhere.com 3000
31 A similar example, transferring a file from another process and passing
33 the expected size to pv:
34 cat file | pv -s 12345 | nc -w 1 somewhere.com 3000
36 A more complicated example using numeric output to feed into the dia‐
38 log(1) program for a full-screen progress display:
39 (tar cf - . \
41 | pv -n -s $(du -sb . | awk '{print $1}') \
42 | gzip -9 > out.tgz) 2>&1 \
43 | dialog --gauge 'Progress' 7 70
44 Taking an image of a disk, skipping errors:
46 pv -EE /dev/your/disk/device > disk-image.img
48 Writing an image back to a disk:
50 pv disk-image.img > /dev/your/disk/device
52 Zeroing a disk:
54 pv < /dev/zero > /dev/your/disk/device
56 Note that if the input size cannot be calculated, and the output is a
58 block device, then the size of the block device will be used and pv
59 will automatically stop at that size as if -S had been given.
60 (Linux only): Watching file descriptor 3 opened by another process
62 1234:
63 pv -d 1234:3
65 (Linux only): Watching all file descriptors used by process 1234:
67 pv -d 1234
69
73 pv takes many options, which are divided into display switches, output
74 modifiers, and general options.
75
79 If no display switches are specified, pv behaves as if -p, -t, -e, -r,
80 and -b had been given (i.e. everything except average rate is switched
81 on). Otherwise, only those display types that are explicitly switched
82 on will be shown.
83 -p, --progress
85 Turn the progress bar on. If standard input is not a file and
86 no size was given (with the -s modifier), the progress bar can‐
87 not indicate how close to completion the transfer is, so it will
88 just move left and right to indicate that data is moving.
89 -t, --timer
91 Turn the timer on. This will display the total elapsed time
92 that pv has been running for.
93 -e, --eta
95 Turn the ETA timer on. This will attempt to guess, based on
96 current transfer rates and the total data size, how long it will
97 be before completion. This option will have no effect if the
98 total data size cannot be determined.
99 -I, --fineta
101 Turn the ETA timer on, but display the estimated local time of
102 arrival instead of time left. When the estimated time is more
103 than 6 hours in the future, the date is shown as well.
104 -r, --rate
106 Turn the rate counter on. This will display the current rate of
107 data transfer.
108 -a, --average-rate
110 Turn the average rate counter on. This will display the current
111 average rate of data transfer (default: last 30s, see --average-
112 rate-window).
113 -b, --bytes
115 Turn the total byte counter on. This will display the total
116 amount of data transferred so far.
117 -8, --bits
119 Display the total bits instead of the total bytes. The output
120 suffix will be "b" instead of "B".
121 -T, --buffer-percent
123 Turn on the transfer buffer percentage display. This will show
124 the percentage of the transfer buffer in use - but see the
125 caveat under %T in the FORMATTING section below. Implies -C.
126 -A, --last-written NUM
128 Show the last NUM bytes written - but see the caveat under %nA
129 in the FORMATTING section below. Implies -C.
130 -F, --format FORMAT
132 Ignore the options -p, -t, -e, -r, -a, -b, -T, and -A, and in‐
133 stead use the format string FORMAT to determine the output for‐
134 mat. See the FORMATTING section below.
135 -n, --numeric
137 Numeric output. Instead of giving a visual indication of
138 progress, pv will give an integer percentage, one per line, on
139 standard error, suitable for piping (via convoluted redirection)
140 into dialog(1). Note that -f is not required if -n is being
141 used.
142 Note that if --numeric is in use, then adding --bytes will cause
144 the number of bytes processed so far to be output instead of a
145 percentage; if --line-mode is also in use as well as --bytes and
146 --numeric, then instead of bytes or a percentage, the number of
147 lines so far is output. And finally, if --timer is added to
148 --numeric, then each output line is prefixed with the elapsed
149 time so far, as a decimal number of seconds.
150 -q, --quiet
152 No output. Useful if the -L option is being used on its own to
153 just limit the transfer rate of a pipe.
154
158 -W, --wait
159 Wait until the first byte has been transferred before showing
160 any progress information or calculating any ETAs. Useful if the
161 program you are piping to or from requires extra information be‐
162 fore it starts, eg piping data into gpg(1) or mcrypt(1) which
163 require a passphrase before data can be processed.
164 -D, --delay-start SEC
166 Wait until SEC seconds have passed before showing any progress
167 information, for example in a script where you only want to show
168 a progress bar if it starts taking a long time. Note that this
169 can be a decimal such as 0.5.
170 -s SIZE, --size SIZE
172 Assume the total amount of data to be transferred is SIZE bytes
173 when calculating percentages and ETAs. The same suffixes of
174 "k", "m" etc can be used as with -L.
175 If SIZE starts with @, the size of file whose name follows the @
177 will be used.
178 Note that --size has no effect if used with -d PID to watch all
180 file descriptors of a process, but will work with -d PID:FD.
181 -l, --line-mode
183 Instead of counting bytes, count lines (newline characters). The
184 progress bar will only move when a new line is found, and the
185 value passed to the -s option will be interpreted as a line
186 count. Note that file sizes are not automatically calculated
187 when this option is used, to avoid having to read all files
188 twice.
189 -0, --null
191 Count lines as null terminated. This option implies
192 --line-mode.
193 -i SEC, --interval SEC
195 Wait SEC seconds between updates. The default is to update ev‐
196 ery second. Note that this can be a decimal such as 0.1.
197 -m SEC, --average-rate-window SEC
199 Compute current average rate over a SEC seconds window for aver‐
200 age rate and ETA calculations (default 30s).
201 -w WIDTH, --width WIDTH
203 Assume the terminal is WIDTH characters wide, instead of trying
204 to work it out (or assuming 80 if it cannot be guessed).
205 -H HEIGHT, --height HEIGHT
207 Assume the terminal is HEIGHT rows high, instead of trying to
208 work it out (or assuming 25 if it cannot be guessed).
209 -N NAME, --name NAME
211 Prefix the output information with NAME. Useful in conjunction
212 with -c if you have a complicated pipeline and you want to be
213 able to tell different parts of it apart.
214 -f, --force
216 Force output. Normally, pv will not output any visual display
217 if standard error is not a terminal. This option forces it to
218 do so.
219 -c, --cursor
221 Use cursor positioning escape sequences instead of just using
222 carriage returns. This is useful in conjunction with -N (name)
223 if you are using multiple pv invocations in a single, long,
224 pipeline.
225
229 -L RATE, --rate-limit RATE
230 Limit the transfer to a maximum of RATE bytes per second. A
231 suffix of "K", "M", "G", or "T" can be added to denote kibibytes
232 (*1024), mebibytes, and so on.
233 -B BYTES, --buffer-size BYTES
235 Use a transfer buffer size of BYTES bytes. A suffix of "K",
236 "M", "G", or "T" can be added to denote kibibytes (*1024),
237 mebibytes, and so on. The default buffer size is the block size
238 of the input file's filesystem multiplied by 32 (512KiB max), or
239 400KiB if the block size cannot be determined. This can be use‐
240 ful on platforms like MacOS which perform better in pipelines
241 with specific buffer sizes such as 1024. Implies -C.
242 -C, --no-splice
244 Never use splice(2), even if it would normally be possible. The
245 splice(2) system call is a more efficient way of transferring
246 data from or to a pipe than regular read(2) and write(2), but
247 means that the transfer buffer may not be used. This prevents
248 -A and -T from working, and makes -B redundant, so using -A, -T,
249 or -B automatically switches on -C. Switching on -C results in
250 a small loss of transfer efficiency. (This option has no effect
251 on systems where splice(2) is unavailable).
252 -E, --skip-errors
254 Ignore read errors by attempting to skip past the offending sec‐
255 tions. The corresponding parts of the output will be null
256 bytes. At first only a few bytes will be skipped, but if there
257 are many errors in a row then the skips will move up to chunks
258 of 512. This is intended to be similar to dd conv=sync,noerror
259 but has not been as thoroughly tested.
260 Specify -E twice to only report a read error once per file, in‐
262 stead of reporting each byte range skipped.
263 -S, --stop-at-size
265 If a size was specified with -s, stop transferring data once
266 that many bytes have been written, instead of continuing to the
267 end of input.
268 -Y, --sync
270 After every write operation, synchronise the buffer caches to
271 disk - see fdatasync(2). This has no effect when the output is
272 a pipe. Using -Y may improve the accuracy of the progress bar
273 when writing to a slow disk.
274 -K, --direct-io
276 Set the O_DIRECT flag on all inputs and outputs, if it is avail‐
277 able. This will minimise the effect of caches, at the cost of
278 performance. Due to memory alignment requirements, it also may
279 cause read or write failures with an error of "Invalid argu‐
280 ment", especially if reading and writing files across a variety
281 of filesystems in a single pv call. Use this option with cau‐
282 tion.
283 -d PID[:FD], --watchfd PID[:FD]
285 Instead of transferring data, watch file descriptor FD of
286 process PID, and show its progress. The pv process will exit
287 when FD either changes to a different file, changes read/write
288 mode, or is closed; other data transfer modifiers - and remote
289 control - may not be used with this option.
290 If only a PID is specified, then that process will be watched,
292 and all regular files and block devices it opens will be shown
293 with a progress bar. The pv process will exit when process PID
294 exits.
295 -R PID, --remote PID
297 If PID is an instance of pv that is already running, -R PID will
298 cause that instance to act as though it had been given this in‐
299 stance's command line instead. For example, if pv -L 123K is
300 running with process ID 9876, then running pv -R 9876 -L 321K
301 will cause it to start using a rate limit of 321KiB instead of
302 123KiB. Note that some options cannot be changed while running,
303 such as -c, -l, -f, -D, -E, and -S.
304
307 -P FILE, --pidfile FILE
308 Save the process ID of pv in FILE. The file will be truncated
309 if it already exists, and will be removed when pv exits. While
310 pv is running, it will contain a single number - the process ID
311 of pv - followed by a newline.
312 -h, --help
314 Print a usage message on standard output and exit successfully.
315 -V, --version
317 Print version information on standard output and exit success‐
318 fully.
319
323 If the -F option is given, then the output format is determined by the
324 given format string. Within that string, the following sequences can
325 be used:
326 %p Progress bar. Expands to fill the remaining space. Should only
328 be specified once. Equivalent to -p.
329 %t Elapsed time. Equivalent to -t.
331 %e ETA as time remaining. Equivalent to -e.
333 %I ETA as local time of completion. Equivalent to -I.
335 %r Current data transfer rate. Equivalent to -r.
337 %a Average data transfer rate. Equivalent to -a.
339 %b Bytes transferred so far (or lines if -l was specified). Equiv‐
341 alent to -b. If --bits was specified, %b shows the bits trans‐
342 ferred so far, not bytes.
343 %T Percentage of the transfer buffer in use. Equivalent to -T.
345 Shows "{----}" if the transfer is being done with splice(2),
346 since splicing to or from pipes does not use the buffer.
347 %nA Show the last n bytes written (e.g. %16A for the last 16
349 bytes). Shows only dots if the transfer is being done with
350 splice(2), since splicing to or from pipes does not use the buf‐
351 fer.
352 %N Name prefix given by -N. Padded to 9 characters with spaces,
354 and suffixed with :.
355 %% A single %.
357 The format string equivalent of turning on all display switches is `%N
359 %b %T %t %r %a %p %e'.
360
364 Some suggested common switch combinations:
365 pv -ptebar
368 Show a progress bar, elapsed time, estimated completion time,
369 byte counter, average rate, and current rate.
370 pv -betlap
372 Show a progress bar, elapsed time, estimated completion time,
373 line counter, and average rate, counting lines instead of bytes.
374 pv -t Show only the elapsed time - useful as a simple timer, e.g.
376 sleep 10m | pv -t.
377 pv -pterb
379 The default behaviour: progress bar, elapsed time, estimated
380 completion time, current rate, and byte counter.
381 On MacOS, it may be useful to specify -B 1024 in a pipeline, as this
384 may improve performance.
385
389 An exit status of 1 indicates a problem with the -R or -P options.
390 Any other exit status is a bitmask of the following:
392 2 One or more files could not be accessed, stat(2)ed, or opened.
395 4 An input file was the same as the output file.
397 8 Internal error with closing a file or moving to the next file.
399 16 There was an error while transferring data from one or more in‐
401 put files.
402 32 A signal was caught that caused an early exit.
404 64 Memory allocation failed.
406 A zero exit status indicates no problems.
409
413 Written by Andrew Wood, with patches submitted by various other people.
414 Please see the package's ACKNOWLEDGEMENTS file for a complete list of
415 contributors.
416
420 The following problems are known to exist in pv:
421 * In some versions of bash(1) and zsh(1), the construct <(pv file‐
423 name) will not output any progress to the terminal when run from
424 an interactive shell, due to the subprocess being run in a sepa‐
425 rate process group from the one that owns the terminal. In
426 these cases, use --force.
427 * The -c option does not work properly on Cygwin without cygserver
429 running, if started near the bottom of the screen (IPC is needed
430 to handle the terminal scrolling). To fix this, start cygserver
431 before using pv -c.
432 * The -R option is not available on Cygwin without cygserver run‐
434 ning (SYSV IPC is needed). To fix this, start cygserver before
435 running the instance of pv you want, at runtime, to change the
436 parameters of.
437 If you find any other problems, please report them.
439
443 Report bugs in pv to pv@ivarch.com or use the contact form linked from
444 the pv home page: <http://www.ivarch.com/programs/pv.shtml>
445
449 cat(1), dialog(1), splice(2), open(2) (for O_DIRECT)
450
453 This is free software, distributed under the ARTISTIC 2.0 license.
454Linux July 2023 PV(1)