[U-Boot] HUSH logical AND/OR expressions

[James Chargin <jimccrown@gmail.com>]

Wolfgang,

Thanks for your contributions.

On 04/28/2015 03:51 PM, Wolfgang Denk wrote:
> Dear Joe,
>
> In message <CANr=Z=YxsT-VOje5jA0k00BSxNROXBOPXMG-Q_8_7jAYN=fJCw@mail.gmail.com> you wrote:
>>
>>> I noticed you asked for a reference to the original hush code that is the
>>> origin for U-Boot's adaptation. I couldn't find a reply to that question. I
>>> also haven't been able to find anything with a quick we search. Do you know
>>> where it did come from?
>>
>> I never got a response, but it appears to be busybox...
>
> Oops, sorry.  Yes, of course it is busybox.
>
> As far as I can tell, it was added around October 2001 to the PPCBoot
> project as part of the PPCBoot v1.1.0 release:
>
> * Added "hush" shell (from Busybox) as alternative command line
>    interpreter, thus enabling powerful command line syntax like
>    if...then...else...fi conditionals or `&&' and '||' constructs
>    ("shell scripts").
>
>    See the README file for information about implementation and usage.
>

I should have thought of this myself. I could have looked in the commit 
history or release notes.

Just for completeness, I tried the commands using busybox:

# busybox|head -1
BusyBox v1.20.2 (2013-07-02 15:49:59 PDT) multi-call binary.
# false && true || echo ECHO
ECHO
# false && false || echo ECHO
ECHO
# true && false || echo ECHO
ECHO
#

-- 
Jim Chargin
AJA Video Systems                       jimc at aja.com
(530) 271-3334                          http://www.aja.com