[U-Boot] [PATCH V2 2/5] fs: implement infra-structure for an 'exists' function

[Simon Glass]

Hi Stephen,

On 27 January 2014 09:03, Stephen Warren <swarren at wwwdotorg.org> wrote:
> On 01/26/2014 08:41 AM, Simon Glass wrote:
>> Hi Stephen,
>>
>> On 23 January 2014 12:56, Stephen Warren <swarren at wwwdotorg.org
>> <mailto:swarren at wwwdotorg.org>> wrote:
>>
>>     From: Stephen Warren <swarren at nvidia.com <mailto:swarren at nvidia.com>>
>>
>>     This could be used in scripts such as:
>>
>>     if exists mmc 0:1 /boot/boot.scr; then
>>         load mmc 0:1 ${scriptaddr} /boot/boot.scr
>>         source ${scriptaddr}
>>     fi
> ...
>> Acked-by: Simon Glass <sjg at chromium.org <mailto:sjg at chromium.org>>
>>
>> Seems useful.
>>
>> In addition, if it is just the error messages you are worried about (and
>> I agree they should be eliminated) I wonder if we should consider adding
>> a -e flag (or similar) to the read command to make it silently fail when
>> the file does not exist? Arguably your code fragment above could be:
>>
>> if load -e mmc 0:1 ${scriptaddr} /boot/boot.scr; then
>>     source ${scriptaddr}
>> fi
>
> That would certainly work, although I think a direct check of
> file-existence is more in line with how a regular Unix shell script
> would work (test -e). I could imagine wanting to test for the existence
> of a file without caring about its contents (e.g. using a file as a flag
> to trigger a firmware upgrade or something)

Given all the parameters, it is bit different from Unix, but test -e
<lots of params> sounds like a nice idea.

Regards,
Simon