(cli/api definitions) Document fern export command (#842)

Author: devalog

fern/products/api-def/ferndef-pages/export-openapi.mdx

@@ -3,21 +3,16 @@ title: Export from Fern Definition to OpenAPI
 description: Export your Fern Definition files to OpenAPI using Fern's OpenAPI generator.
 ---
 
-To prevent lock-in to the Fern Definition format, we provide a generator that will export your Fern Def files to OpenAPI 3.1. 
-This lets you switch to using OpenAPI at any time, or use your API definition with OpenAPI tools.
-To convert your Fern Definition to OpenAPI, use the `fern-openapi` generator. 
+To prevent lock-in to the Fern Definition format, you can export your API definition to OpenAPI 3.1 at any time [using the `fern export` command](/cli-api-reference/cli-reference/commands#fern-export). 
 
-Update your `generators.yml` file:
+If you have multiple APIs defined in your `fern/apis/` folder, use `--api` to specify which API to export.
 
-<CodeBlock title="generators.yml">
-```yaml
-- name: fernapi/fern-openapi
-  version: 0.0.31
-  config:
-    format: yaml # options are yaml or json
-  output:
-    location: local-file-system
-    path: ../openapi # relative path to output location
-```
-</CodeBlock>
+    <CodeBlock title="terminal">
+    ```bash
+    fern export path/to/openapi.yml
+    fern export path/to/openapi.json
 
+    # Specify API to export
+    fern export --api public-api path/to/openapi.yml
+    ```
+    </CodeBlock>

fern/products/cli-api-reference/pages/commands.mdx

@@ -12,6 +12,7 @@ hideOnThisPage: true
 | [`fern upgrade`](#fern-upgrade) | Update Fern CLI & generators to latest versions |
 | [`fern login`](#fern-login) | Login to Fern CLI via GitHub or Google |
 | [`fern logout`](#fern-logout) | Log out of the Fern CLI |
+| [`fern export`](#fern-export) | Export an OpenAPI spec for your API |
 
 ## Documentation Commands
 
@@ -140,6 +141,33 @@ hideOnThisPage: true
     </Tip>
   </Accordion>
 
+  <Accordion title="fern export">
+
+    Use `fern export` to generate an OpenAPI spec for your API.
+
+    This command is useful when you've defined your API in a format other than OpenAPI (such as the [Fern Definition](/api-definitions/ferndef/overview)) and need to export it as an OpenAPI spec for integration with other tools or services.
+
+
+    <CodeBlock title="terminal">
+    ```bash
+    fern export [--api <api>] path/to/openapi.yml
+    fern export [--api <api>] path/to/openapi.json
+    ```
+    </CodeBlock>
+
+    ### api
+
+    Use `--api` to specify which API to export when you have multiple APIs defined in your `fern/apis/` folder.
+
+        <CodeBlock title="terminal">
+    ```bash
+    fern export --api public-api path/to/openapi.yml
+    fern export --api public-api path/to/openapi.json
+    ```
+    </CodeBlock>
+
+  </Accordion>
+
   <Accordion title="fern generate">
     Use `fern generate` to run the Fern compiler and create SDKs for your API.
 

fern/products/sdks/snippets/initialize-fern-folder-intro.mdx

@@ -1,5 +1,5 @@
 You can initialize your fern folder with either a Fern Definition or OpenAPI specification.
 
   <Tip>
-    You can always convert a Fern Definition to OpenAPI or OpenAPI to a Fern Definition later on.
+    You can always convert a [Fern Definition to OpenAPI](/api-definitions/ferndef/export-openapi) or OpenAPI to a Fern Definition later on.
   </Tip>