Re: gSystem->Exec() : memory of variables

Hi,

I don't understand what you're trying to do (not enough experience with Athena, I guess). But it looks like you're better off writing out a bash file that you then invoke through Exec().

Cheers, Axel.

Marc Escalier wrote on 03/09/2011 02:26 PM:
> Hi,
>
> thanks to the help of many of you, i continue with definition of python,
> obtaining this :
>
> //begin definition of python :
> gSystem->Setenv("PYTHON_VER","2.6");
> gSystem->Setenv("PYTHON_DIR","'/usr/local/python/python-${PYTHON_VER}'");
> gSystem->Setenv("export PATH","'${PYTHON_DIR}/bin:${PATH}'");
> gSystem->Setenv("export CFLAGS","'-L /usr/local/python/python-2.6/lib'");
> gSystem->Setenv("LD_LIBRARY_PATH","'$PYTHON_DIR/lib:$LD_LIBRARY_PATH'");
>
> // gSystem->Exec("python"); //this commands works
> //end definition of python
>
> //gSystem->Setenv("amiGetDatasetEVNTInfo","'python
> /afs/cern.ch/atlas/software/releases/16.6.2/AtlasCore/16.6.2/Database/Bookkeeping/AMIClients/pyAMI/python/amiGetDatasetEVNTInfo.py'");
>
> gSystem->Exec("asetup 16.6.2");
> gSystem->Setenv("amiGetDatasetEVNTInfo","python
> /afs/cern.ch/atlas/software/releases/16.6.2/AtlasCore/16.6.2/Database/Bookkeeping/AMIClients/pyAMI/python/amiGetDatasetEVNTInfo.py");
>
> gSystem->Exec("`echo $amiGetDatasetEVNTInfo`");
>
> but the amiGetDatasetEVNTInfo crashes only because one needs to define
> asetup 16.6.2, which i can't do *inside* root
>
> ======
> Axel Naumann a écrit :

>> Hi Marc,
>>
>> That's not what Georg wrote - note the '$' sign.
>>
>> Anyway, you could probably assign it to a C++ variable and use that,
>> instead of an environment variable.
>>
>> Cheers, Axel.
>>
>>
>> Marc Escalier wrote on 03/09/2011 01:51 PM:
>>  
>>> thanks, i try to do an alias within root :
>>> ==>
>>>
>>> gSystem->Setenv("amiGetDatasetEVNTInfo","'python
>>> /afs/cern.ch/atlas/software/releases/16.6.2/AtlasCore/16.6.2/Database/Bookkeeping/AMIClients/pyAMI/python/amiGetDatasetEVNTInfo.py'");
>>>
>>>
>>> gSystem->Exec("`amiGetDatasetEVNTInfo`");
>>>
>>> gives :
>>> sh: amiGetDatasetEVNTInfo: command not found
>>>
>>> while in unix :
>>> ccali16% alias amiGetDatasetEVNTInfo='python
>>> /afs/cern.ch/atlas/software/releases/16.6.2/AtlasCore/16.6.2/Database/Bookkeeping/AMIClients/pyAMI/python/amiGetDatasetEVNTInfo.py'
>>>
>>>
>>> ccali16% amiGetDatasetEVNTInfo
>>>
>>> does something
>>>
>>> =============================
>>> Georg Troska a écrit :
>>>    
>>>> Hi,
>>>>
>>>> a variable is not an alias.
>>>> doing in bash
>>>>
>>>> # A="xclock"
>>>> # echo $A
>>>>
>>>> will not work either.
>>>> Probably not the best way, but
>>>>
>>>> root[] # gSystem->SetEnv("A","xclock")
>>>> root[] # gSystem->Exec("`echo $A`")
>>>>
>>>> will work. Georg
>>>>
>>>>
>>>>  
>>>>      
>>>>> but the folllowing doesn't "work":
>>>>>
>>>>> root [1] gSystem->Setenv("amiGetDatasetEVNTInfo","'python
>>>>> /afs/cern.ch/atlas/software/releases/16.6.2/AtlasCore/16.6.2/Database/Bookkeeping/AMIClients/pyAMI/python/amiGetDatasetEVNTInfo.py'")
>>>>>
>>>>>
>>>>> root [2] gSystem->Exec("amiGetDatasetEVNTInfo")
>>>>> sh: amiGetDatasetEVNTInfo: command not found
>>>>>
>>>>> while in unix :
>>>>> alias amiGetDatasetEVNTInfo='python
>>>>> /afs/cern.ch/atlas/software/releases/16.6.2/AtlasCore/16.6.2/Database/Bookkeeping/AMIClients/pyAMI/python/amiGetDatasetEVNTInfo.py
>>>>>
>>>>>
>>>>> amiGetDatasetENVInfo
>>>>> "works"
>>>>>
>>>>> would you have a hint ?
>>>>>
>>>>> ===============
>>>>>
>>>>> Dario Berzano a écrit :
>>>>>           
>>>>>> Hello,
>>>>>>
>>>>>>  each gSystem->Exec(), just like the standard C system() function,
>>>>>> opens a new shell ("man system" says /bin/sh) with a brand new
>>>>>> environment.
>>>>>>
>>>>>> But in ROOT you can set environment variables that are seen by
>>>>>> subshells launched either via gSystem->Exec() or
>>>>>> gSystem->OpenPipe()/GetFromPipe(): for instance you can play with
>>>>>> the following code:
>>>>>>
>>>>>>  // The environment variable COUNTER is set to 0
>>>>>>  gSystem->Setenv("COUNTER", "0");
>>>>>>
>>>>>>  // COUNTER is incremented in subshells and its value is set to
>>>>>> ROOT's
>>>>>>  // (*not* shell's) environment
>>>>>>  for (Int_t i=0; i<100; i++) {
>>>>>>    gSystem->Setenv("COUNTER", gSystem->GetFromPipe("expr $COUNTER +
>>>>>> 1"));
>>>>>>  }
>>>>>>
>>>>>>  // A subshell is spawned to echo the value of envvar COUNTER
>>>>>>  gSystem->Exec("echo Variable COUNTER has value $COUNTER");
>>>>>>
>>>>>> Please note that opening/closing 100 subshells just to increment a
>>>>>> variable's value 100 times isn't very performance-friendly...
>>>>>>
>>>>>> Cheers,
>>>>>> -- 
>>>>>> : Dario Berzano
>>>>>> : INFN & Università - Torino, Italy
>>>>>> : Wiki: http://newton.ph.unito.it/~berzano
>>>>>> : GPG: http://newton.ph.unito.it/~berzano/gpg
>>>>>> : Mobile: +39 348 72 22 520
>>>>>>
>>>>>>
>>>>>> Le 9 mars 2011 à 11:53, Marc Escalier a écrit :
>>>>>>
>>>>>>  
>>>>>>               
>>>>>>> Hello,
>>>>>>>
>>>>>>> in root, there are the methods TSystem::Exec() and
>>>>>>> TSystem::GetFromPipe which have the same behaviour for the
>>>>>>> following issue :
>>>>>>>
>>>>>>> if one does in unix :
>>>>>>> a=3
>>>>>>> echo $a
>>>>>>> it works
>>>>>>>
>>>>>>> but in root :
>>>>>>> if ones does :
>>>>>>> gSystem->Exec("b=3);
>>>>>>> gSystem->Exec("echo $b")
>>>>>>> it will "forget" the b
>>>>>>>
>>>>>>> only this works :
>>>>>>> gSystem->Exec("c=3;echo $c")
>>>>>>>
>>>>>>> ==>
>>>>>>> is there a way to have the memory of the variables for several
>>>>>>> gSystem->Exec() commands ?
>>>>>>> (in order to do some instructions ones, and some others inside a
>>>>>>> loop)
>>>>>>>
>>>>>>> (i tried also with export, but it doesn't help)
>>>>>>>
>>>>>>> thanks
>>>>>>>                        
>>>>>>  
>>>>>>                 
>>>>         
>>>