How to generate random number of garbage files of random size

Question

I am trying to write a script that will generate a random number of garbage files of random length. Ideally 1-50 files of length 100Kb-100Mb. I have written this script but does only generate 2 files. I would also like the filename to be the string "RanDoM" followed by a random number.

What am i doing wrong?

#!/bin/bash

ntimes=$(( ( RANDOM % 50 )  + 1 ))

for i in {1.. $ntimes}
do
   dd if=/dev/urandom of=$RANDOM bs=1K count=$(((RANDOM % 10000) + 1))
done

Use sparse files? `seq 50 | xargs -I XXX bash -c 'truncate -s ${RANDOM}b file.XXX'` — bishop, Sep 05 '18 at 16:33

score 1 · Answer 1 · answered Sep 05 '18 at 16:17

The construct {1..$var} does not work because brace expansion happens before variable expansion. From the bash man page:

   The order of expansions is: brace expansion; tilde expansion, parameter
   and  variable expansion, arithmetic expansion, and command substitution
   (done in a left-to-right fashion); word splitting; and pathname  expan-
   sion.

You can get the functionality you want using an external tool like seq:

for i in $(seq 1 $ntimes); do
  dd ...
done

How to generate random number of garbage files of random size

1 Answers1