[DNX#2006040142000857] [U-Boot-Users] test variable existence in hush

[DENX Support System <support@denx.de>]

Hello list,

inside the automatic U-Boot patch tracking system a new ticket
[DNX#2006040142000857] was created:

<snip>
> On Mon, 22 Aug 2005 14:21:58 +0200 Wolfgang Denk wrote:
> 
> >I cannot confirm this. The only part of hush which is  involved  here
> >is the && processing which works fine for me..
> >
> >"test" is NOT a hush builtin.
> 
> I hit the send button too early...
> 
> Yes, "test" is not a hush builtin, but it is only available if the hush
> parser is enabled.
> 
> >Sure:
> >
> >TRAB # foo=
> >TRAB # test -n "$foo" && echo yes
> >TRAB # test -n "$foo" || echo no
> >no
> >TRAB # test "$foo" && echo yes
> >TRAB # test "$foo" || echo no
> >no
> >TRAB # foo=dummy
> >TRAB # test -n "$foo" && echo yes
> >yes
> >TRAB # test -n "$foo" || echo no
> >TRAB # test "$foo" && echo yes
> >TRAB # test "$foo" || echo no
> >no
> >
> >THe only problem I see is with "test -z":
> >
> >	TRAB # foo=
> >	TRAB # test -z "$foo" && echo yes
> >	TRAB # test -z "$foo" || echo no
> >	no
> >but
> >	TRAB # test -z "" && echo yes
> >	yes
> >	TRAB # test -z "" || echo no
> >	TRAB # 
> 
> No, I think this is misleading. A quick debugging session showed that
> the problem is not the "test" command itself. With 'test -z ""' and
> 'test -n ""', the command will correctly see three arguments. However,
> with 'test -n "$foo"' and 'test -z "$foo"' (and empty $foo), the command
> will only get two arguments which always results in a return value of 1.
> That's why 'test -n' seems to work.
> 
> Regards,
>   Andreas Engel
> 
> 
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</snip>

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