&#x2F;dev&#x2F;urandom while entropy available is low:<p><pre><code>  $ rngtest -c 200000 -b 2000 &lt; &#x2F;dev&#x2F;urandom  
  .....

  rngtest: bits received from input: 4000000032
  rngtest: FIPS 140-2 successes: 199848
  rngtest: FIPS 140-2 failures: 152
  rngtest: FIPS 140-2(2001-10-10) Monobit: 24
  rngtest: FIPS 140-2(2001-10-10) Poker: 15 
  rngtest: FIPS 140-2(2001-10-10) Runs: 60
  rngtest: FIPS 140-2(2001-10-10) Long run: 54
  rngtest: FIPS 140-2(2001-10-10) Continuous run: 0
  rngtest: input channel speed: (min=3.782; avg=63.752; max=82.928)Mibits&#x2F;s
  rngtest: FIPS tests speed: (min=4.559; avg=158.909; max=194.627)Mibits&#x2F;s
  rngtest: Program run time: 83882495 microseconds
</code></pre>
It gets much worse.