>>>>       2) At the time of this test campaign, the shebang line of vdev
>>>> scripts was #!/bin/dash, which doesn't work in Busybox. It should be
>>>> replaced by #!/bin/sh which works in all cases.
>>> This isn't necessarily true. Both dash and the usual busybox sh are
>>> forks of the Amquist shell (ash) which is supposed to be enable to
>>> execute scripts written in the Bourne shell language/ for the
>>> standardized /bin/sh but they also provide extensions of their own (eg,
>>> like bash, dash supports lexically scoped function variables but the
>>> Bourne/ standard shell doesn't). The busybox ash can also compiled w/o
>>> certain features, eg, arithmetic expansion.

>>      There's no theory behind that. It's just practical and the result
>> of experimenting.

>>      The way Busybox works is all applications are links to
>> /bin/busybox. When invoqued, /bin/busybox
> ... looks at argv[0] and invokes the corresponding embedded
> program. "Everybody knows that" (well, not everybody but everybody who
> ever worked with busybox) .

>>      On the other hand, the default shell in Debian, the one invoked by
>> /bin/sh, is dash. I guess in every distro /bin/sh points to the
>> ~POSIX-compliant shell. Therefore '#!/bin/sh' should just work
>> everywhere.
> It should be the name of a shell capable of running Bourne/ standard
> shell scripts. But this may not work if the /bin/dash in the original
> script was there for a reason, ie, it was using dash features.