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Runtime file
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.. toctree::
   :maxdepth: 1

You can use a runtime file to give to *Tochnog* data on the fly (while it is running). The runtime file will be read at the start of each time step. The runtime file needs to have the same name as the input file, with the extension *run* instead of *dat* however. Suppose the name of the normal input file is *beam.dat*, then the name of the runtime file is *beam.run*.

The runtime file always needs to be ended with *two* :ref:`end_data` statements.

As a typical example you can use this runtime file when you are doing a long calculation and you decide while the calculation is running that you want extra output. Suppose the normal input file *tochnog.dat* contains:

.. code-block::

   ...
   control_timestep 100
   ...

Then you can decide to get some extra *GID* plotting files, while *Tochnog* is already running, by using the runtime file *tochnog.run* with:

.. code-block::

   ...
   control_print_gid 100 -yes
   end_data end_data

When you want to deactivate the printing of *GID* files again then set the runtime file to:

.. code-block::

   ...
   control_print_gid 100 -no
   end_data end_data

As a special option, you can use :ref:`exit_tochnog` *-yes* in the runtime file; then *Tochnog* will exit the calculation after printing the complete database and *GID* files.

After the runtime file is read, it will be automatically deleted by *Tochnog*.