[Qemu-devel] tests/Makefile.include non-portable use of $RANDOM

[Peter Maydell]

Currently our test makefile does

   MALLOC_PERTURB_=$${MALLOC_PERTURB_:-$$((RANDOM % 255 + 1))}

This works on bash, but $RANDOM is bash-specific.
On dash, it doesn't do what we want, but it does do something:

$ echo $((RANDOM % 255 + 1))
1

On NetBSD the shell complains:
# echo $((RANDOM % 255 + 1))
-sh: arith: syntax error: "RANDOM % 255 + 1"

and so 'make check' doesn't work.

Any suggestions for something more portable?
https://unix.stackexchange.com/questions/140750/generate-random-numbers-in-specific-range
suggests
  awk 'BEGIN{srand(); print int(1+rand()*256)}'
and of course there are similar things possible with perl et al.

Or we could just have the makefile check whether we have bash,
and if not then set
  RANDOM=4

(thus putting NetBSD into the same boat as all our dash users).

Opinions?

thanks
-- PMM