PUMP(1)								       PUMP(1)

NAME
       pump - copy asynchronously via a large circular buffer

SYNOPSIS
       pump [ -b iando ] [ -d sleepms ] [ -f ofile ] [ -i ireadsize ] [ -k KB-
       buf ] [ -o owritesize ] [ -s start-KB ] [ file ... ]

DESCRIPTION
       Pump copies files (or standard input if none)  to  standard  output  by
       using  two processes, one reading and one writing, sharing a large cir‐
       cular buffer, thus permitting the reading process to get ahead  of  the
       writing	process	 if the output device is slow (e.g., an optical disc).
       This in turn can keep the output device busy.  The pipeline can approx‐
       imate this, but pipe buffering is limited to 64K bytes, which is fairly
       modest.

       Options are:

       -b     sets the size of read and write operations to iando bytes.   The
	      default size is 8 kilobytes.

       -d     causes the output process to sleep for sleepms milliseconds ini‐
	      tially, giving the reading process time to  accumulate  data  in
	      the buffer.

       -f     writes ofile rather than standard output

       -i     sets the size of read operations to ireadsize bytes.

       -k     allocates	 a circular buffer of KB-buf kilobytes rather than the
	      default 5000 kilobytes.

       -o     sets the size of write operations to owritesize bytes.

       -s     prevents output until start-KB kilobytes have been read.

EXAMPLES
       Append a venti(8) arena to a DVD or BD quickly.
	      cdfs
	      venti/rdarena arena0 arena.3 |
		   pump -b 65536 -k 51200 >/mnt/cd/wd/arena.3

SOURCE
       /sys/src/cmd/pump.c

SEE ALSO
       cp(1), dd(1), ecp(1), cdfs(4)

BUGS
       Pump processes spin while waiting for the circular buffer  to  fill  or
       drain.

								       PUMP(1)

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