Hi @rraallvv,
I’d suggest you to just generate a base bitrise config then iterate on that, adding the things you need.
Using the Bitrise CLI (https://www.bitrise.io/cli) you can generate a base config by:
cd /into/your/git/root
bitrise init --minimal
The minimal config will include a Script step. You can do anything with the Script step, e.g. running the commands you ran in your travis config.
Please see a practical intro to the CLI and editor at: How to experiment with Bitrise configs locally, on your Mac/Linux
If you’d have any questions just let us know!