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 circular 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 `dd | dd' can
approximate 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 millisec-
onds initially, giving the reading process time to accu-
mulate 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.
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