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.TH "bup-random" "1" "0.33.3" "Bup 0.33.3" ""
.hy
.SH NAME
.PP
bup-random - generate a stream of random output
.SH SYNOPSIS
.PP
bup random [-S seed] [-fv] <numbytes>
.SH DESCRIPTION
.PP
\f[V]bup random\f[R] produces a stream of pseudorandom output bytes to
stdout.
Note: the bytes are \f[I]not\f[R] generated using a cryptographic
algorithm and should never be used for security.
.PP
Note that the stream of random bytes will be identical every time
\f[V]bup random\f[R] is run, unless you provide a different
\f[V]seed\f[R] value.
This is intentional: the purpose of this program is to be able to run
repeatable tests on large amounts of data, so we want identical data
every time.
.PP
\f[V]bup random\f[R] generates about 240 megabytes per second on a
modern test system (Intel Core2), which is faster than you could achieve
by reading data from most disks.
Thus, it can be helpful when running microbenchmarks.
.SH OPTIONS
.TP
<numbytes>
the number of bytes of data to generate.
Can be used with the suffices \f[V]k\f[R], \f[V]M\f[R], or \f[V]G\f[R]
to indicate kilobytes, megabytes, or gigabytes, respectively.
.TP
-S, --seed=\f[I]seed\f[R]
use the given value to seed the pseudorandom number generator.
The generated output stream will be identical for every stream seeded
with the same value.
The default seed is 1.
A seed value of 0 is equivalent to 1.
.TP
-f, --force
generate output even if stdout is a tty.
(Generating random data to a tty is generally considered ill-advised,
but you can do if you really want.)
.TP
-v, --verbose
print a progress message showing the number of bytes that has been
output so far.
.SH EXAMPLES
.IP
.nf
\f[C]
$ bup random 1k | sha1sum
2108c55d0a2687c8dacf9192677c58437a55db71  -

$ bup random -S1 1k | sha1sum
2108c55d0a2687c8dacf9192677c58437a55db71  -

$ bup random -S2 1k | sha1sum
f71acb90e135d98dad7efc136e8d2cc30573e71a  -

$ time bup random 1G >/dev/null
Random: 1024 Mbytes, done.

real   0m4.261s
user   0m4.048s
sys    0m0.172s

$ bup random 1G | bup split -t --bench
Random: 1024 Mbytes, done.
bup: 1048576.00kbytes in 18.59 secs = 56417.78 kbytes/sec
1092599b9c7b2909652ef1e6edac0796bfbfc573
\f[R]
.fi
.SH BUP
.PP
Part of the \f[V]bup\f[R](1) suite.
.SH AUTHORS
Avery Pennarun <apenwarr@gmail.com>.