Looks like you ought to call popen for collecting outputs.

> On Nov 26, 2017, at 11:51 PM, bill lam <[email protected]> wrote:
> 
> In j805 2!:0 always failed for this both on linux and mac, On j806,
> change had been made on the linux branch but not on mac. The code
> starts from line 42 of
> the file xh.c
> https://github.com/jsoftware/jsource/blob/master/jsrc/xh.c
> 
> note the command passed to 2!:0 is appended with redirection for a tmp
> file which is used to collect result to report to J.
> 
> 'cmd .... ' > tmpfile
> if the cmd itself already contains an output redirection such as what
> you did, then there will be 2 output redirections in the resultant
> cmd,
> 'bla bla > fork,6  > tmpfile'
> perhaps the shell interpreter used in system() is not smart enough to
> handle it.
> 
> What is the expected standard behavior for it? Why hostcmd_j_ can
> solve it? I dun know.
> 
> 
> 
> On Mon, Nov 27, 2017 at 1:07 PM, J. Patrick Harrington
> <[email protected]> wrote:
>> Many thanks. The expression
>>    hostcmd_j_ =: [: 2!:0 '(' , ,&' || true)' solves the problem I had with
>> just 2!:0. But is there an explination
>> why an exprssion of the form 2!:0 'foo.exe <infile >outfile' should
>> work on some machines and fail on others, when both are running the
>> same version of J? I'm afraid my grasp of unix scripting is too poor
>> to understand just what hostcmd_j_ does.
>> 
>> Patrick
>> 
>> 
>> On Sat, 25 Nov 2017, Joey K Tuttle wrote:
>>> 
>>> Chris,
>>> Thanks for the credit - and I'm glad to see that hostcmd_j_ is commonly
>>> available.
>>> 
>>> But, to be fair, I plagiarized the definition from Martin Neitzel more
>>> than 23 years ago...
>>> 
>>> My servers invoke it many thousands of times a day in various monitoring
>>> scripts - and I use it often in CLI sessions as well.
>>> I like the fact that it always returns a result (as well as echoing stderr
>>> output to my CLI session), which desire is what Martin responded to all
>>> those years ago.
>>> 
>>> - joey
>>> 
>>> 
>>>> On 2017Nov 25, at 12:14, chris burke <[email protected]> wrote:
>>>> 
>>>> hostcmd_j_ is Joey's cover for 2!:0, e.g. see
>>>> www.jsoftware.com/pipermail/programming/2017-April/047204.html
>>>> 
>>>> On Sat, Nov 25, 2017 at 12:06 PM, J. Patrick Harrington
>>>> <[email protected]>
>>>> wrote:
>>>> 
>>>>> Sorry, I meant "returning with no screen output'
>>>>> I am now running the full program with hostcmd_j_ for 2!:0.
>>>>> It's chugging away, hasn't failed yet. :-)
>>>>> 
>>>>> 
>>>>> On Sat, 25 Nov 2017, J. Patrick Harrington wrote:
>>>>> 
>>>>>> Chris,
>>>>>> 
>>>>>> That test works. I just tried
>>>>>> 
>>>>>> hostcmd_j_ '../synmod.exe < fort.5 >fort.6'
>>>>>> 
>>>>>> and that works as well, returning with screen output, and writing
>>>>>> successfully to fort.6. So hostcmd_j_  ~: 2!:0
>>> 
>>> 
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