Command Line Subcommands Challenge

Introduction

This challenge aims to test your ability to define and use subcommands with their own set of flags in Golang.

Skills Graph

%%%%{init: {'theme':'neutral'}}%%%% flowchart RL go(("`Go`")) -.-> go/CommandLineandEnvironmentGroup(["`Command Line and Environment`"]) go/CommandLineandEnvironmentGroup -.-> go/command_line("`Command Line`") subgraph Lab Skills go/command_line -.-> lab-15384{{"`Command Line Subcommands (Challenge)`"}} end

Command Line Subcommands

You are required to create a program that supports two subcommands, foo and bar, each with its own set of flags. The foo subcommand should have two flags, enable and name, while the bar subcommand should have one flag, level.

Requirements

The program should use the flag package to define and parse flags.
The foo subcommand should have two flags, enable and name, both of type string.
The bar subcommand should have one flag, level, of type int.
The program should print an error message if an invalid subcommand is provided.
The program should print the values of the flags for the subcommand that is invoked.

Example

$ go build command-line-subcommands.go

## First invoke the foo subcommand.
$ ./command-line-subcommands foo -enable -name=joe a1 a2
subcommand 'foo'
enable: true
name: joe
tail: [a1 a2]

## Now try bar.
$ ./command-line-subcommands bar -level 8 a1
subcommand 'bar'
level: 8
tail: [a1]

## But bar won't accept foo's flags.
$ ./command-line-subcommands bar -enable a1
flag provided but not defined: -enable
Usage of bar:
-level int
level

## Next we'll look at environment variables, another common
## way to parameterize programs.

Summary

In this challenge, you learned how to define and use subcommands with their own set of flags in Golang using the flag package. You also learned how to parse the flags for each subcommand and access the trailing positional arguments.