1bup-random(1)                                                    bup-random(1)
2
3
4

NAME

6       bup-random - generate a stream of random output
7

SYNOPSIS

9       bup random [-S seed] [-fv] <numbytes>
10

DESCRIPTION

12       bup random  produces  a  stream of pseudorandom output bytes to stdout.
13       Note: the bytes are not generated using a cryptographic  algorithm  and
14       should never be used for security.
15
16       Note  that  the  stream  of  random  bytes will be identical every time
17       bup random is run, unless you provide a different seed value.  This  is
18       intentional:  the  purpose of this program is to be able to run repeat‐
19       able tests on large amounts of data, so we want  identical  data  every
20       time.
21
22       bup random  generates  about  240 megabytes per second on a modern test
23       system (Intel Core2), which is faster than you could achieve by reading
24       data from most disks.  Thus, it can be helpful when running microbench‐
25       marks.
26

OPTIONS

28       <numbytes>
29              the number of bytes of data to generate.  Can be used  with  the
30              suffices  k,  M, or G to indicate kilobytes, megabytes, or giga‐
31              bytes, respectively.
32
33       -S, --seed=seed
34              use the given value to seed the pseudorandom  number  generator.
35              The  generated  output stream will be identical for every stream
36              seeded with the same value.  The default seed is 1.  A seed val‐
37              ue of 0 is equivalent to 1.
38
39       -f, --force
40              generate output even if stdout is a tty.  (Generating random da‐
41              ta to a tty is generally considered ill-advised, but you can  do
42              if you really want.)
43
44       -v, --verbose
45              print  a  progress  message showing the number of bytes that has
46              been output so far.
47

EXAMPLES

49              $ bup random 1k | sha1sum
50              2108c55d0a2687c8dacf9192677c58437a55db71  -
51
52              $ bup random -S1 1k | sha1sum
53              2108c55d0a2687c8dacf9192677c58437a55db71  -
54
55              $ bup random -S2 1k | sha1sum
56              f71acb90e135d98dad7efc136e8d2cc30573e71a  -
57
58              $ time bup random 1G >/dev/null
59              Random: 1024 Mbytes, done.
60
61              real   0m4.261s
62              user   0m4.048s
63              sys    0m0.172s
64
65              $ bup random 1G | bup split -t --bench
66              Random: 1024 Mbytes, done.
67              bup: 1048576.00kbytes in 18.59 secs = 56417.78 kbytes/sec
68              1092599b9c7b2909652ef1e6edac0796bfbfc573
69

BUP

71       Part of the bup(1) suite.
72

AUTHORS

74       Avery Pennarun <apenwarr@gmail.com>.
75
76
77
78Bup 0.29.1                        2017-03-26                     bup-random(1)