# Configuration via config.ini

Configuration of the Pioreactors is through .ini files. On the worker Raspberry Pis, these live in /home/pi/.pioreactor. There are two .ini files: a shared config.ini and a unit-specific unit_config.ini file. The config.ini file is the same across all units. The unit_config.ini can be blank, or can have settings that overwrite those found in the shared config.ini. See image below:

### How to edit the configuration files from the PioreactorApp and command line.

All the .ini files come from the leader unit. They are stored in /home/pi/.pioreactor - one config.ini and a config_<unitName>.ini for each Pioreactor unit. The command pios sync-configs will deploy the .ini files to their correct unit. Editing the .ini files on the leader is correct workflow, as any edits on the worker units will be overwritten on the next pios sync-configs.

One can programmatically, or by hand, edit the config_<unitName>.ini files to create varying parameters in an experiment. Running pios sync-configs will deploy the config files.

### How to edit the configuration files from PioreactorUI

In the PioreactorUI, the sidebar contains a link to Configuration From there, any config.ini file can be edited. Clicking [Save] will save the new configuration and will deploy the new configuration to the proper Pioreactor unit.

### Example config.ini

If you need a reference config.ini, or to replace parts of yours, here's our default one. To use it, you'll need to make some changes, specifically to network.leader.

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