Re: Seeding $RANDOM in a subshell

[Chet Ramey]

Chris F.A. Johnson wrote:
>    On various platforms, with versions of bash from 1.14 to 3.0, I
>    get:
>
> $ RANDOM=1234567890; echo $RANDOM
> 2599
> $ RANDOM=1234567890; echo $RANDOM
> 2599
>
>    That's as it should be. But when I put that in a subshell (2.05b
>    and 3.00):
>
> $ ( RANDOM=1234567890; echo $RANDOM )
> 18681
> $ ( RANDOM=1234567890; echo $RANDOM )
> 20498
> $ ( RANDOM=1234567890; echo $RANDOM )
> 22315
>
>    Bash 1.14 (as well as pdksh and ksh93) produces the same number
>    every time.

Bash was changed at some point in the past to re-seed the random number
generator when a subshell was started, so the random sequence differed
in the parent and the subshell.

I have since made two changes that will address your concerns:  the
rng is only re-seeded once per subshell, and assigning a value to
RANDOM in the subshell counts as re-seeding.

Chet