[U-Boot] [PATCH v3 5/5] RFC: tegra: Convert to using environment files

[Stephen Warren <swarren@wwwdotorg.org>]

On 10/28/2013 02:50 PM, Simon Glass wrote:
> Hi Stephen,
> 
> On Mon, Oct 28, 2013 at 2:41 PM, Stephen Warren <swarren@wwwdotorg.org> wrote:
>> On 10/28/2013 02:34 PM, Simon Glass wrote:
>>> Hi Stephen,
>>>
>>> On Mon, Oct 28, 2013 at 1:59 PM, Stephen Warren <swarren@wwwdotorg.org> wrote:
>>>> On 10/25/2013 11:01 PM, Simon Glass wrote:
>>>>> This seems more intuitive that the current #define way of doing things.
>>>>> The resulting code is shorter, avoids the quoting and line continuation
>>>>> pain, and also improves the clumsy way that stdio variables are created:

>>>>> diff --git a/board/nvidia/env/common.env b/board/nvidia/env/common.env
>>>>
>>>>> +bootcmd_mmc0=setenv devnum 0; run mmc_boot
>>>>> +bootcmd_mmc1=setenv devnum 1; run mmc_booxt
>>>>> +boot_targets+= mmc1 mmc0
>>>>
>>>> I still don't see why = needs no space before/after, but += needs no
>>>> space before, but a space after. That simply looks like a typo to me,
>>>> and I'd be inclined to fix it were I editing this file. If a sed script
>>>> can't handle more flexible white-space, perhaps use Python or perhaps
>>>> Perl instead?
>>>
>>> The old code was similar, in that it had a space after the quote.
>>>
>>> We need the string to contain "mmc0 mmc1 usb0 dhcp" or perhaps "mmc0
>>> mmc1". I chose to add a space at the start of each string, but
>>> certainly we need a space somewhere, or we get "mmc0mmc1usb0dhcp".
>>
>> Oh, I see. I thought the space was part of the += syntax, not the value.
>> Perhaps to make that more obvious, you could allow:
>>
>> # No space added to value
>> var+=value
...
>> var += "value1 value2"
>>
>> # One space included at start of addition to value
>> var+=" value1 value2"
>> var+= " value1 value2"
>> var +=" value1 value2"
>> var += " value1 value2"
> 
> I was deliberately trying to avoid using quotes, since then it is
> really hard when you actually mean 'quote'.

Hmm. On the other hand, quoting is standard syntax in any scripting
language.

> For example at present you can put this in an env script at present,
> but how would you do it if quotes are special?

Just escape it; " goes around the string and \" or "" within the string.
This seems pretty common...