.. _interface-analysis_drivers-system-file_tag:

""""""""
file_tag
""""""""


Tag each parameters & results file name with the function evaluation
number


.. toctree::
   :hidden:
   :maxdepth: 1



**Specification**

- *Alias:* None

- *Arguments:* None

- *Default:* no tagging


**Description**


If this keyword is used, Dakota will append a period and the function evaluation
number to the names of the parameter and results files.

*Default Behavior*
If this keyword is omitted, the default is no file tagging.

*Usage Tips*

- File tagging is most useful when multiple function evaluations are  running simultaneously using files in a shared disk space. The  analysis driver will be able to infer the function evaluation number  from the file names.


- Note that when the ``file_save`` keyword is used, Dakota  automatically renames parameters and results files, giving them tags  after execution of the analysis driver if they otherwise would be  overwritten by the next evaluation.



**Examples**


If the following is included in the ``interface`` section of the Dakota
input:


.. code-block::

      parameters_file = params.in
      results_file = results.out
      file_tag


Then for the 3rd evaluation, Dakota will write ``params``.in.3, and will expect
``results``.out.3 to be written by the analysis driver.


