Re: Use of == in shell scripts

[Andreas Oberritter <obi@opendreambox.org>]

On 10/26/2010 06:29 PM, Michael Smith wrote:
> Andreas Oberritter wrote:
>> On 10/26/2010 05:31 PM, Andreas Oberritter wrote:
>>> How about splitting it into 5 patches?
>>>
>>> - classes (7 files)
>>> - contrib (4 files)
>>> - recipes/*/*.bb (24 files)
>>> - recipes/*/*.inc (14 files)
>>> - other files in recipes except recipes/obsolete (11 files)
>>
>> Or how about those 37 patches?
>>
>> http://git.opendreambox.org/?p=obi/openembedded.git;a=shortlog;h=refs/heads/equality-operator
>>
>>
>> Rationale:
>> - bbclasses: 1 patch per file
>> - contrib and recipes: 1 patch per directory
> 
> For the series:
> 
> Acked-By: Michael Smith <msmith@cbnco.com>
> 
> Except this one:
> 
> http://git.opendreambox.org/?p=obi/openembedded.git;a=commitdiff;h=ad7b2c9ab0c305034c39d2efc5a52789965bb5c2
> 
> 
> where some lines had == twice, looks like your sed may not have caught it.

Thanks for spotting! I've updated the patch series and added your ack.

> BTW, some of the files have constructs like this:
> 
> if [ "x$HAS_MADWIFI" = "x1" ]
> 
> I think this "x" business is for old broken shells that can't handle an
> empty quoted string as the first argument. Does anyone know the standard
> well enough to say? I figure [ "" = "1" ] should be legal everywhere.
> This is just a pet peeve/bike shed on my part.

Autotools use constructs like that everywhere, so it's likely increasing
portability while decreasing readability.

A random forum post suggests that some versions of '[' have problems, if
the first operand equals '!' or '(' [1].

It's not easy to search for [ or test or x on google. ;-)

Regards,
Andreas

[1]
http://www.techtalkz.com/unix/78138-testing-equality-bash-scripts.html#post329122