R devel - Nov 2010 - Problem with system2(), directing STDERR to a file

According to ?system2, I should be able to direct the output of STDERR to a
file by giving the filename as a character vector to the "stderr"
argument.

But here is what happens.

Given a ruby script test.rb (with its executable bit set):

#!/usr/bin/env ruby
STDOUT.puts "stdout"
STDERR.puts "stderr"

And the following R code:
> t <- tempfile()
> res <- system2("./test.rb", stdout=TRUE, stderr=t)
stderr
> res
[1] "stdout"
> file.exists(t)
[1] FALSE

I would expect the file t to exist and contain "stderr", and I would
expect
not to see "stderr" in the console.

Also, there is a typo in the man page - the command is listed as
"system" in
the Description instead of "system2".

The reverse behavior does work correctly:
> res <- system2("./test.rb", stdout=t, stderr="")
stderr
> file.exists(t)
[1] TRUE


Thanks!
Dan

	[[alternative HTML version deleted]]

Looking at help for tempfile,

"tempfile" returns a vector of character strings which can be used as 
names for temporary files.
 
and

 For "tempfile" a character vector giving the names of possible
     (temporary) files. Note that no files are generated by
"tempfile".


try a file.create(t) after tempfile()

cheers,

Keith


Dan Tenenbaum wrote:
> According to ?system2, I should be able to direct the output of STDERR to a
> file by giving the filename as a character vector to the "stderr"
argument.
>
> But here is what happens.
>
> Given a ruby script test.rb (with its executable bit set):
>
> #!/usr/bin/env ruby
> STDOUT.puts "stdout"
> STDERR.puts "stderr"
>
> And the following R code:
>
>   
>> t <- tempfile()
>> res <- system2("./test.rb", stdout=TRUE, stderr=t)
>>     
> stderr
>   
>> res
>>     
> [1] "stdout"
>   
>> file.exists(t)
>>     
> [1] FALSE
>
> I would expect the file t to exist and contain "stderr", and I
would expect
> not to see "stderr" in the console.
>
> Also, there is a typo in the man page - the command is listed as
"system" in
> the Description instead of "system2".
>
> The reverse behavior does work correctly:
>   
>> res <- system2("./test.rb", stdout=t, stderr="")
>>     
> stderr
>   
>> file.exists(t)
>>     
> [1] TRUE
>
>
> Thanks!
> Dan
>
> 	[[alternative HTML version deleted]]
>
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> https://stat.ethz.ch/mailman/listinfo/r-devel
>   
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