Add bash completion for gaiad and gaiacli (#3334)

client/flags.go

@@ -2,6 +2,7 @@ package client
 
 import (
 	"fmt"
+	"os"
 	"strconv"
 
 	"github.com/spf13/cobra"
@@ -162,3 +163,35 @@ func ParseGas(gasStr string) (simulateAndExecute bool, gas uint64, err error) {
 	}
 	return
 }
+
+// NewCompletionCmd builds a cobra.Command that generate bash completion
+// scripts for the given root command. If hidden is true, the command
+// will not show up in the root command's list of available commands.
+func NewCompletionCmd(rootCmd *cobra.Command, hidden bool) *cobra.Command {
+	flagZsh := "zsh"
+	cmd := &cobra.Command{
+		Use:   "completion",
+		Short: "Generate Bash/Zsh completion script to STDOUT",
+		Long: `To load completion script run
+
+. <(completion_script)
+
+To configure your bash shell to load completions for each session add to your bashrc
+
+# ~/.bashrc or ~/.profile
+. <(completion_script)
+`,
+		RunE: func(_ *cobra.Command, _ []string) error {
+			if viper.GetBool(flagZsh) {
+				return rootCmd.GenZshCompletion(os.Stdout)
+			}
+			return rootCmd.GenBashCompletion(os.Stdout)
+		},
+		Hidden: hidden,
+		Args:   cobra.NoArgs,
+	}
+
+	cmd.Flags().Bool(flagZsh, false, "Generate Zsh completion script")
+
+	return cmd
+}