Performing the same operation on a set of snapshots with ``snapshots_exec``
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Very often, it is useful to perform the same operation on a set of similar files, for example,
the output snapshots of a simulation. **pNbody** offers a command to do so::

  snapshots_exe

Just provide a set of files as well as a command to execute on the ``nb`` object, and it will to it::

  snapshots_exec snapshots/* --exec "print(nb.nbody)"

This command is very useful to extract particles for a set of snapshots and store the sub-snapshots in a dedicated directory::

  snapshots_exec snapshots/* --exec="nb = nb.select('stars')" -o snap
  

Scripts
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``snapshots_exec``
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.. program-output:: snapshots_exec -h