@Ruiqi Liu Thank you for reaching out.
Azure Cosmos DB supports Linux and provides a Docker image for running the emulator on Linux. But the docker file is only available for windows. You can find more information about running the emulator on Linux in the following link: https://docs.microsoft.com/en-us/azure/cosmos-db/linux-emulator. If you have any further questions, please let me know.
Regards,
Oury