Re: [PATCH] Replace 'test "${var+set}" = set' with 'test -n "${var+set}"'

[Eric Blake]

On 04/08/2015 04:25 PM, Eric Blake wrote:
> And in modern shell, 'test -n ...' is strictly equivalent to 'test ...'
> (not so in ancient shell, but those are getting fewer and farther
> between) - if we did appropriate pre-filtering tests, we could get away
> with 15 bytes:
> 
> test "${var+y}"

Or even 13:

test ${var+y}

Does anyone know of portability flaws in broken test implementations
that might bite us? This one actually works on Solaris /bin/sh, without
affecting $?.

> 
> 
> On 04/08/2015 03:11 PM, Paul Eggert wrote:
>> Isn't '${var+:} false' faster yet?
>          ^^^^^^^^^^^^^^  14 bytes
> 

and shorter than Paul's solution.  But I'm worried if some other shell
mis-handles it.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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