Add 'manpage' command to generate manual pages

cmd/restic/cmd_manpage.go

@@ -0,0 +1,58 @@
+package main
+
+import (
+	"os"
+
+	"github.com/restic/restic/internal/errors"
+	"github.com/spf13/cobra"
+	"github.com/spf13/cobra/doc"
+)
+
+var cmdManpage = &cobra.Command{
+	Use:   "manpage [command]",
+	Short: "generate manual pages",
+	Long: `
+The "manpage" command generates a manual page for a single command. It can also
+be used to write all manual pages to a directory. If the output directory is
+set and no command is specified, all manpages are written to the directory.
+`,
+	RunE: runManpage,
+}
+
+var manpageOpts = struct {
+	OutputDir string
+}{}
+
+func init() {
+	cmdRoot.AddCommand(cmdManpage)
+	fs := cmdManpage.Flags()
+	fs.StringVar(&manpageOpts.OutputDir, "output-dir", "", "write man pages to this `directory`")
+}
+
+func runManpage(cmd *cobra.Command, args []string) error {
+	header := &doc.GenManHeader{
+		Title:   "restic backup",
+		Section: "1",
+		Source:  "generated by `restic manpage`",
+	}
+
+	dir := manpageOpts.OutputDir
+	if dir != "" {
+		Verbosef("writing man pages to directory %v\n", dir)
+		return doc.GenManTree(cmdRoot, header, dir)
+	}
+
+	if len(args) > 1 {
+		return errors.Fatalf("more than one command given: %v", args)
+	}
+
+	name := args[0]
+
+	for _, cmd := range cmdRoot.Commands() {
+		if cmd.Name() == name {
+			return doc.GenMan(cmd, header, os.Stdout)
+		}
+	}
+
+	return errors.Fatalf("command %q is not known", args)
+}