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% bup-random(1) Bup %BUP_VERSION%
% Avery Pennarun <apenwarr@gmail.com>
% %BUP_DATE%
# NAME
bup-random - generate a stream of random output
# SYNOPSIS
bup random [-S seed] [-fv] \<numbytes\>
# DESCRIPTION
`bup random` produces a stream of pseudorandom output bytes to
stdout. Note: the bytes are *not* generated using a
cryptographic algorithm and should never be used for
security.
Note that the stream of random bytes will be identical
every time `bup random` is run, unless you provide a
different `seed` 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.
`bup random` 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.
# OPTIONS
\<numbytes\>
: the number of bytes of data to generate. Can be used
with the suffices `k`, `M`, or `G` to indicate
kilobytes, megabytes, or gigabytes, respectively.
-S, \--seed=*seed*
: 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.
-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.)
-v, \--verbose
: print a progress message showing the number of bytes that
has been output so far.
# EXAMPLES
$ 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
# BUP
Part of the `bup`(1) suite.
|
