Customizations

If default completion isnt sufficient additional customizations are available

• custom auto-completion
• customizing completion command

Custom auto-completion

package main

import (
    "fmt"
    "log"
    "os"
    "context"

    "github.com/urfave/cli/v3"
)

func main() {
    tasks := []string{"cook", "clean", "laundry", "eat", "sleep", "code"}

    cmd := &cli.Command{
        EnableShellCompletion: true,
        Commands: []*cli.Command{
            {
                Name:    "complete",
                Aliases: []string{"c"},
                Usage:   "complete a task on the list",
                Action: func(ctx context.Context, cmd *cli.Command) error {
                    fmt.Println("completed task: ", cmd.Args().First())
                    return nil
                },
                ShellComplete: func(ctx context.Context, cmd *cli.Command) {
                    // This will complete if no args are passed
                    if cmd.NArg() > 0 {
                        return
                    }
                    for _, t := range tasks {
                        fmt.Println(t)
                    }
                },
            },
        },
    }

    if err := cmd.Run(context.Background(), os.Args); err != nil {
        log.Fatal(err)
    }
}

Customize a completion command

By default, a completion command is hidden, meaning the command isn't included in the help message. You can customize it by setting root Command's ConfigureShellCompletionCommand.

package main

import (
    "context"
    "fmt"
    "log"
    "os"

    "github.com/urfave/cli/v3"
)

func main() {
    cmd := &cli.Command{
        Name: "greet",
        // EnableShellCompletion is unnecessary
        ConfigureShellCompletionCommand: func(cmd *cli.Command) { // cmd is a completion command
            cmd.Hidden = false // Make a completion command public
            cmd.Usage = "..." // Customize Usage
            cmd.Description = "..." // Customize Description
        },
        Commands: []*cli.Command{
            {
                Name:  "hello",
                Usage: "Say hello",
                Action: func(ctx context.Context, cmd *cli.Command) error {
                    fmt.Println("Hello")
                    return nil
                },
            },
        },
    }

    if err := cmd.Run(context.Background(), os.Args); err != nil {
        log.Fatal(err)
    }
}

Customization

The default shell completion flag (--generate-shell-completion) is defined as cli.EnableShellCompletion, and may be redefined if desired, e.g.:

package main

import (
    "log"
    "os"
    "context"

    "github.com/urfave/cli/v3"
)

func main() {
    cmd := &cli.Command{
        EnableShellCompletion: true,
        Commands: []*cli.Command{
            {
                Name: "wat",
            },
        },
    }

    if err := cmd.Run(context.Background(), os.Args); err != nil {
        log.Fatal(err)
    }
}