Provided by: bup-doc_0.29-3_all bug


       bup-random - generate a stream of random output


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


       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.


              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.


              $ 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


       Part of the bup(1) suite.


       Avery Pennarun <>.