Creating Custom Commands

One of CLILib's strengths is how easy it is to create your own commands. Implement the Command interface with the required fields and the behaviour you want.

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✏️ Basic command example

object HelloCmd : Command {
    override val description = "Say hello to the user"
    override val usage = "hello <name>"
    override val aliases = listOf("hello", "hi")
    override val minArgs = 1
    override val maxArgs = 1

    override fun run(args: List<String>): Boolean {
        println("Hello, ${'$'}{args[0]}!")
        return true
    }
}

Then simply register the command:

CmdRegister.register(HelloCmd)

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📌 Required fields

• description – short description
• usage – how to use the command (shown in help)
• aliases – names the command can be called by
• run(args: List<String>) – execution logic

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⚙️ Useful optional fields

• minArgs / maxArgs — expected number of arguments
• requiresFile / fileExtension — validate file paths
• commands — define subcommands or flags (e.g. -h, --list)
• longDescription — longer description shown with help <command>

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🔁 Dynamic commands with JSON

You can also create simple commands from a .json file using mkcmd.

mkcmd example.json

Example example.json:

{
  "description": "Example command via JSON",
  "longDescription": "This command was created from a JSON file.",
  "usage": "exjson <arg>",
  "aliases": ["exjson"],
  "minArgs": 1,
  "maxArgs": 1,
  "requiresFile": false,
  "fileExtension": "",
  "run": "print arg[0]"
}

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✅ Best practices

• Call validateArgs(args, this) at the start of run
• Store temporary results in lastCmdDump (so they can be used with var)
• Use println sparingly (only for useful messages)
• Give aliases clear and short names

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With these tools you can extend CLILib to support any functionality you need — from system commands to external API integrations.