Re: Processing Macros in background

Hi Thomas,

I agree, what you do (interactive vs. not) makes sense.

The prompt actually *talks* to the TTY: it asks the TTY about the type of terminal it is, whether it supports DEL etc. For that the prompt needs the TTY. It can also not do it and disable all editing / prompt features. That's what it does when the input or output is not connected to a terminal. So this

echo '{printf("HELLO\n");}' | root -b -q | less

works even without TTY. It happily runs in the background:

(echo '{printf("HELLO\n");}' | root -b -q ) &

I hope that explains this context a bit better :-)

Cheers, Axel.

Thomas Lauf wrote on 07/06/2010 10:53 AM:
> Hello Axel, Rooters!
>
> My idea at the moment is to implement an option for my program which
> determines whether to start it as an TRint (interactive) or just as a
> simple TApplication. In the first case I have my command line user
> interface, the second is for the special case described below.
>
> The small example below does the job, the price is that I have to
> trigger the execution of the macro files manually. But this seems to
> solve my problem, so I pay it willingly :)
>
> main.cxx:
> #include "TSystem.h"
> #include "Riostream.h"
> #include "TMacro.h"
> #include "TApplication.h"
> #include "TRint.h"
> #include "TObjArray.h"
> #include "TObjString.h"
>
> Int_t main( Int_t Argc, Char_t** Argv ) {
> Bool_t Interactive=kTRUE;
>
> for( Int_t i=0; i<Argc; ++i ) {
> cout << "Arg[" << i << "]: " << Argv[i] << endl;
> if( !strcmp(Argv[i], "-noninteractive") ) Interactive=kFALSE;
> }
>
> TApplication* theApp;
>
> if( Interactive ) {
> cout << "--- interactive mode ---" << endl;
> theApp = new TRint( "App", &Argc, Argv );
> } else {
> cout << "--- non interactive mode ---" << endl;
> theApp = new TApplication( "App", &Argc, Argv );
> }
>
> cout << "Running..." << endl;
> if( Interactive ) {
> theApp->Run( kTRUE );
>
> } else {
> cout << "Processing input files..." << endl;
> TIter Next( theApp->InputFiles() );
> TObjString* ObjStr;
>
> while( (ObjStr = (TObjString*) Next()) ) {
> theApp->ProcessLine( Form( ".x %s", ObjStr->String().Data() ) );
> }
> }
> cout << "Quitting..." << endl;
> }
>
> Test.C
> {
> #include "Riostream.h"
> cout<< "Hello World" << endl;
> }
>
> One thing that still puzzels me is: if background processes cannot write
> to the TTY, why do I see the ROOT Logo when doing this:
>
> ]> root -b &
>
> The output stops when the ROOT prompt would be displayed. Guess I have
> to update my understanding of "tty" and "standard output". Until now
> this was identical for me...
>
> Thanks for the help so far!
>
> Thomas
>
>
> Axel Naumann wrote:

>> background processes cannot write to the TTY. If you have an idea (or a
>> patch! :-) how to get it to work nevertheless then please let us know.
>>
>> Cheers, Axel.
>>
>> Thomas Lauf wrote on 07/05/2010 04:59 PM:
>>> Hello ROOTers,
>>>
>>> is there a way to process a ROOT macro in the background?
>>>
>>> Consider this simple macro Test.C:
>>> {
>>>   cout << "Hello World" << endl;
>>> }
>>>
>>> If I call ROOT to process it
>>> ]> root -q -l Test.C
>>>
>>> in the shell I get the expected output:
>>>
>>> root [0]
>>> Processing Test.C...
>>> Hello World
>>> ]>
>>>
>>> But if I want ROOT to process it in the background
>>> I get no output until I fetch the process to foreground again
>>> ]> root -q -l Test.C &
>>> [4] 16584
>>> ]> fg
>>> root -q -l Test.C
>>> root [0]
>>> Processing Test.C...
>>> Hello World
>>> ]>
>>>
>>> Is there a way to make this work?
>>>
>>> The thing is I have a application (e.g. Prog1) which calls another one
>>> (e.g. Prog2) to do some calculation. Prog2 uses Rint as user interface.
>>> The call from Prog1 succeeds as long as it is run in foreground. If run
>>> in the background I run into the same problem as shown above.
>>>
>>> Regards
>>>
>>> Thomas Lauf