Cobra: Error from RootCmd.PersistentPreRunE printed twice, with usage string

[ahmetb]

I have a PersistentPreRunE set on my RootCmd. It is simply:

func check(cmd *cobra.Command, args []string) error { return errors.New("foo error") }

when I run my command, I get:

$ ./my-tool Error: foo error
Usage:
  my-tool my-subcommand [flags]

Flags:
  -h, --help   help for list

Global Flags:
  -p, --project string   Google Cloud project ID

foo error

Problems:

1. why is foo error printed twice (at the very beginning and at the very end)?
2. why is the full usage string printed? Is there a way to prevent it?

[bogem]

1. I think, it's because you print an error returned from cmd.Execute(). Execute func already prints an error if it occurred in PersistentPreRunE.
2. You can prevent it with cmd.SilenceUsage = true.

[ahmetb]

@bogem thanks for the answer. When I SilenceUsage=true, duplicate printing looks worse:

$ my-tool -s
Error: unknown shorthand flag: 's' in -s
unknown shorthand flag: 's' in -s

[bogem]

Probably, it's because you print an error returned from cmd.Execute() like this:

if err := cmd.Execute(); if err != nil {
    fmt.Println(err)
}

but cmd.Execute() prints errors automatically as I said before. So just delete all error handling in your app and leave only cmd.Execute() call.

[ahmetb]

Thanks.

[ahmetb]

actually my main.go is already just:

func main() { cmd.Execute() }

and yet I'm still getting errors printed twice, so I'll reopen this.

[ahmetb]

oh turns out I had this in root.go

func Execute() {
    if err := RootCmd.Execute(); err != nil {
        fmt.Println(err)
        os.Exit(1)
    }
}

[rayjohnson]

That part in the rootCmd is generated by the cobra command line tool when generating framework. Should it?

[pecigonzalo]

@bogem I got hit by the same issue as @rayjohnson. Do you know if it should?

The README also shows an example which contains the PrintLn

[weibeld]

Maybe it should really be removed from the Cobra generator tool, as it is confusing, especially for beginners, who are the most likely ones to use the Cobra generator.