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<h1 class="title">bup-random(1) Bup debian/0.29-3</h1>
<h2 class="author">Avery Pennarun <a href="mailto:apenwarr@gmail.com">apenwarr@gmail.com</a></h2>
<h3 class="date">2017-04-01</h3>
</div>
<h1 id="name">NAME</h1>
<p>bup-random - generate a stream of random output</p>
<h1 id="synopsis">SYNOPSIS</h1>
<p>bup random [-S seed] [-fv] <numbytes></p>
<h1 id="description">DESCRIPTION</h1>
<p><code>bup random</code> produces a stream of pseudorandom output bytes to stdout. Note: the bytes are <em>not</em> generated using a cryptographic algorithm and should never be used for security.</p>
<p>Note that the stream of random bytes will be identical every time <code>bup random</code> is run, unless you provide a different <code>seed</code> 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.</p>
<p><code>bup random</code> 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.</p>
<h1 id="options">OPTIONS</h1>
<dl>
<dt><numbytes></dt>
<dd>the number of bytes of data to generate. Can be used with the suffices <code>k</code>, <code>M</code>, or <code>G</code> to indicate kilobytes, megabytes, or gigabytes, respectively.
</dd>
<dt>-S, --seed=<em>seed</em></dt>
<dd>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.
</dd>
<dt>-f, --force</dt>
<dd>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.)
</dd>
<dt>-v, --verbose</dt>
<dd>print a progress message showing the number of bytes that has been output so far.
</dd>
</dl>
<h1 id="examples">EXAMPLES</h1>
<pre><code>$ 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</code></pre>
<h1 id="bup">BUP</h1>
<p>Part of the <code>bup</code>(1) suite.</p>
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