[U-Boot] set and test a local variable in a script

[U-Boot] set and test a local variable in a script

[Andreas Neubacher]

hi,

i'm trying to set a local variable and test the variable in an 
if-then-else script ...
but it's somehow a bit weird!?

- set variable "nea" to 0
- create a script "x" and run .... OK
- modify variable "nea" to 1
- run script "x" again ... NOK?!

... what i'm doing wrong  -  the behavior is the same with 2013.10 and 
2014.01



 >U-Boot# nea=0
 >U-Boot# setenv x "if itest 1 -eq $nea; then echo var1; else echo var0; 
fi;"
 >U-Boot# run x
 >var0
 >U-Boot# nea=1
 >U-Boot# run x
 >var0            <<<<<----- so now i should get the "var1" as a result
 >U-Boot# echo $nea
 >1

 >U-Boot# setenv x "if itest 1 -eq $nea; then echo var1; else echo var0; 
fi;"
 >U-Boot# run x
 >var1          <<<<<------- after i set the script "x" again it's 
working ... ?!


br & thx for any hint,
Andy

[U-Boot] set and test a local variable in a script

[Wolfgang Denk]

Dear Andreas,

In message <5470D48C.1080103@gmx.at> you wrote:
> 
> i'm trying to set a local variable and test the variable in an 
> if-then-else script ...
> but it's somehow a bit weird!?

Not really weird; you just have to be a bit careful about quoting
rules...

> - set variable "nea" to 0
> - create a script "x" and run .... OK
> - modify variable "nea" to 1
> - run script "x" again ... NOK?!
> 
> ... what i'm doing wrong  -  the behavior is the same with 2013.10 and 
> 2014.01

...and it would be the same if you were testing with a regular shell on
the Linux command line.

Actually this is something I always recommend: if you see some strange
behaviour, first try to do the same in a standard shell environment,
and debug it there.


>  >U-Boot# nea=0
>  >U-Boot# setenv x "if itest 1 -eq $nea; then echo var1; else echo var0; 
> fi;"

It would have been a good idea here todo a "printenv x" to check what
was actually stored in the variable - this would have shown your
problem.  The thing is, you want to keep the '$nea' notation in the
variable, so you can evaluate the variable when you run that macro.
However, inside double quotes (") variable substitution takes place,
so above command is equivalent to

    setenv x "if itest 1 -eq 0; then echo var1; else echo var0; fi;"

>  >U-Boot# run x
>  >var0
>  >U-Boot# nea=1
>  >U-Boot# run x
>  >var0            <<<<<----- so now i should get the "var1" as a result
>  >U-Boot# echo $nea
>  >1
 
Use printenv to verify what is stored in the variable x, and you will
understand this.


Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
Today is the yesterday you worried about tomorrow.

[U-Boot] set and test a local variable in a script

[Andreas Neubacher]

hi,

many, many, many thx for your quick response ... now it works, and i 
know why it hasn't  :)

br,
Andy


On 22.11.2014 23:56, Wolfgang Denk wrote:
> Dear Andreas,
>
> In message <5470D48C.1080103@gmx.at> you wrote:
>> i'm trying to set a local variable and test the variable in an
>> if-then-else script ...
>> but it's somehow a bit weird!?
> Not really weird; you just have to be a bit careful about quoting
> rules...
>
>> - set variable "nea" to 0
>> - create a script "x" and run .... OK
>> - modify variable "nea" to 1
>> - run script "x" again ... NOK?!
>>
>> ... what i'm doing wrong  -  the behavior is the same with 2013.10 and
>> 2014.01
> ...and it would be the same if you were testing with a regular shell on
> the Linux command line.
>
> Actually this is something I always recommend: if you see some strange
> behaviour, first try to do the same in a standard shell environment,
> and debug it there.
>
>
>>   >U-Boot# nea=0
>>   >U-Boot# setenv x "if itest 1 -eq $nea; then echo var1; else echo var0;
>> fi;"
> It would have been a good idea here todo a "printenv x" to check what
> was actually stored in the variable - this would have shown your
> problem.  The thing is, you want to keep the '$nea' notation in the
> variable, so you can evaluate the variable when you run that macro.
> However, inside double quotes (") variable substitution takes place,
> so above command is equivalent to
>
>      setenv x "if itest 1 -eq 0; then echo var1; else echo var0; fi;"
>
>>   >U-Boot# run x
>>   >var0
>>   >U-Boot# nea=1
>>   >U-Boot# run x
>>   >var0            <<<<<----- so now i should get the "var1" as a result
>>   >U-Boot# echo $nea
>>   >1
>   
> Use printenv to verify what is stored in the variable x, and you will
> understand this.
>
>
> Best regards,
>
> Wolfgang Denk
>

[U-Boot] set and test a local variable in a script

[Wolfgang Denk]

Dear Andreas,

In message <547211BA.7080603@gmx.at> you wrote:
> 
> many, many, many thx for your quick response ... now it works, and i 
> know why it hasn't  :)

I'm glad I was able to help.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
If the car industry behaved like the computer industry over the  last
30  years, a Rolls-Royce would cost $5, get 300 miles per gallon, and
blow up once a year killing all passengers inside.