result:

      ```yaml
      services:
        myservice:
          # ...
          command: python otherapp.py
      ```

   - For the multi-value options `ports`, `expose`, `external_links`, `dns`, `dns_search`, and `tmpfs`, Compose concatenates both sets of values:

      original service:

      ```yaml
      services:
        myservice:
          # ...
          expose:
            - "3000"
      ```

      local service:

      ```yaml
      services:
        myservice:
          # ...
          expose:
            - "4000"
            - "5000"
      ```

      result:

      ```yaml
      services:
        myservice:
          # ...
          expose:
            - "3000"
            - "4000"
            - "5000"
      ```

   - In the case of `environment`, `labels`, `volumes`, and `devices`, Compose "merges" entries together with locally defined values taking precedence. For `environment` and `labels`, the environment variable or label name determines which value is used:

      original service:

      ```yaml
      services:
        myservice:
          # ...
          environment:
            - FOO=original
            - BAR=original
      ```

      local service:

      ```yaml
      services:
        myservice:
          # ...
          environment:
            - BAR=local
            - BAZ=local
      ```

     result:

      ```yaml
      services:
        myservice:
          # ...
          environment:
            - FOO=original
            - BAR=local
            - BAZ=local
      ```

   - Entries for `volumes` and `devices` are merged using the mount path in the container:

      original service:

      ```yaml
      services:
        myservice:
          # ...
          volumes:
            - ./original:/foo
            - ./original:/bar
      ```

      local service:

      ```yaml
      services:
        myservice:
          # ...
          volumes:
            - ./local:/bar
            - ./local:/baz
      ```

      result:

      ```yaml
      services:
        myservice:
          # ...
          volumes:
            - ./original:/foo
            - ./local:/bar
            - ./local:/baz
      ```

For more merging rules, see [Merge and override](/reference/compose-file/merge.md) in the Compose Specification. 

### Additional information

- Using `-f` is optional. If not provided, Compose searches the working directory and its parent directories for a `compose.yaml` and a `compose.override.yaml` file. You must supply at least the `compose.yaml` file. If both files exist on the same directory level, Compose combines them into a single configuration.

- You can use a `-f` with `-` (dash) as the filename to read the configuration from `stdin`. For example: 
   ```console
   $ docker compose -f - <<EOF
     webapp:
       image: examples/web
       ports:
        - "8000:8000"
       volumes:
        - "/data"
       environment:
        - DEBUG=1
     EOF
   ```
   
   When `stdin` is used, all paths in the configuration are relative to the current working directory.
   
- You can use the `-f` flag to specify a path to a Compose file that is not located in the current directory, either from the command line or by setting up a [COMPOSE_FILE environment variable](../environment-variables/envvars.md#compose_file) in your shell or in an environment file.

   For example, if you are running the [Compose Rails sample](https://github.com/docker/awesome-compose/tree/master/official-documentation-samples/rails/README.md), and have a `compose.yaml` file in a directory called `sandbox/rails`. You can use a command like [docker compose pull](/reference/cli/docker/compose/pull.md) to get the postgres image for the `db` service from anywhere by using the `-f` flag as follows: `docker compose -f ~/sandbox/rails/compose.yaml pull db`