ref: e4b842056c1b63bafae9b5b1347366955b757730
dir: /sys/man/1/pump/
.TH PUMP 1 .SH NAME pump \- copy asynchronously via a large circular buffer .SH SYNOPSIS .B pump [ .B -b .I iando ] [ .B -d .I sleepms ] [ .B -f .I ofile ] [ .B -i .I ireadsize ] [ .B -k .I KB-buf ] [ .B -o .I owritesize ] [ .B -s .I start-KB ] [ .I file \&... ] .SH DESCRIPTION .I Pump copies .IR 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 .L "dd | dd" can approximate this, but pipe buffering is limited to 64K bytes, which is fairly modest. .PP Options are: .TF \fL-m .TP .B -b sets the size of .I read and .I write operations to .I iando bytes. The default size is 8 kilobytes. .TP .B -d causes the output process to sleep for .I sleepms milliseconds initially, giving the reading process time to accumulate data in the buffer. .TP .B -f writes .I ofile rather than standard output .TP .B -i sets the size of .I read operations to .I ireadsize bytes. .TP .B -k allocates a circular buffer of .I KB-buf kilobytes rather than the default 5000 kilobytes. .TP .B -o sets the size of .I write operations to .I owritesize bytes. .TP .B -s prevents output until .I start-KB kilobytes have been read. .SH EXAMPLES Append a .IR venti (8) arena to a DVD or BD quickly. .PD 0 .IP .EX cdfs venti/rdarena arena0 arena.3 | pump -b 65536 -k 51200 >/mnt/cd/wd/arena.3 .EE .PD .\" .SH FILES .SH SOURCE .B /sys/src/cmd/pump.c .SH SEE ALSO .IR cp (1), .IR dd (1), .IR ecp (1), .IR cdfs (4) .SH BUGS .I Pump processes spin while waiting for the circular buffer to fill or drain.