bup-random(1) bup-random(1)
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 in-
tentional: 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 microbench-
marks.
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 giga-
bytes, 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.
AUTHORS
Avery Pennarun ]8;;mailto:apenwarr@gmail.com\apenwarr@gmail.com]8;;\
Bup 0.33.7 2025-01-11 bup-random(1)
Generated by dwww version 1.16 on Sat Oct 3 05:36:28 CEST 2026.