# Generating ReStructured Text Docs For Your Own cobra.Command
Generating ReST pages from a cobra command is incredibly easy. An example is as follows:
```go
package main
import (
"log"
"github.com/spf13/cobra"
"github.com/spf13/cobra/doc"
)
func main() {
cmd := &cobra.Command{
Use: "test",
Short: "my test program",
}
err := doc.GenReSTTree(cmd, "/tmp")
if err != nil {
log.Fatal(err)
}
}
```
That will get you a ReST document `/tmp/test.rst`
## Generate ReST docs for the entire command tree
This program can actually generate docs for the kubectl command in the kubernetes project
```go
package main
import (
"log"
"io/ioutil"
"os"
"k8s.io/kubernetes/pkg/kubectl/cmd"
cmdutil "k8s.io/kubernetes/pkg/kubectl/cmd/util"
"github.com/spf13/cobra/doc"
)
func main() {
kubectl := cmd.NewKubectlCommand(cmdutil.NewFactory(nil), os.Stdin, ioutil.Discard, ioutil.Discard)
err := doc.GenReSTTree(kubectl, "./")
if err != nil {
log.Fatal(err)
}
}
```
This will generate a whole series of files, one for each command in the tree, in the directory specified (in this case "./")
## Generate ReST docs for a single command
You may wish to have more control over the output, or only generate for a single command, instead of the entire command tree. If this is the case you may prefer to `GenReST` instead of `GenReSTTree`
```go
out := new(bytes.Buffer)
err := doc.GenReST(cmd, out)
if err != nil {
log.Fatal(err)
}
```
This will write the ReST doc for ONLY "cmd" into the out, buffer.
## Customize the output
Both `GenReST` and `GenReSTTree` have alternate versions with callbacks to get some control of the output:
```go
func GenReSTTreeCustom(cmd *Command, dir string, filePrepender func(string) string, linkHandler func(string, string) string) error {
//...
}
```
```go
func GenReSTCustom(cmd *Command, out *bytes.Buffer, linkHandler func(string, string) string) error {
//...
}
```
The `filePrepender` will prepend the return value given the full filepath to the rendered ReST file. A common use case is to add front matter to use the generated documentation with [Hugo](http://gohugo.io/):
```go
const fmTemplate = `---
date: %s
title: "%s"
slug: %s
url: %s
---
`
filePrepender := func(filename string) string {
now := time.Now().Format(time.RFC3339)
name := filepath.Base(filename)
base := strings.TrimSuffix(name, path.Ext(name))
url := "/commands/" + strings.ToLower(base) + "/"
return fmt.Sprintf(fmTemplate, now, strings.Replace(base, "_", " ", -1), base, url)
}
```
The `linkHandler` can be used to customize the rendered links to the commands, given a command name and reference. This is useful while converting rst to html or while generating documentation with tools like Sphinx where `:ref:` is used:
```go
// Sphinx cross-referencing format
linkHandler := func(name, ref string) string {
return fmt.Sprintf(":ref:`%s <%s>`", name, ref)
}
```
