shell

var Capture = func(ctx context.Context, dir, name string, args ...string) (Result, error) {
	return run(ctx, dir, nil, name, args...)
}

Capture runs name in dir and collects its output. A non-zero exit is a Result, not an error: the driver contract reserves an exit code with a meaning, so classifying codes belongs to the caller. Only a command that could not start at all is an error here.

var CaptureInput = func(ctx context.Context, dir, input, name string, args ...string) (Result, error) {
	return run(ctx, dir, strings.NewReader(input), name, args...)
}

CaptureInput is Capture with input on the command's stdin: a driver's write verb reads the task it creates from there.

var Has = func(name string) bool {
	_, err := exec.LookPath(name)

	return err == nil
}

Has reports whether name is on PATH.

var Passthrough = func(ctx context.Context, dir, name string, args ...string) error {
	cmd := exec.CommandContext(ctx, name, args...)
	cmd.Dir = dir
	cmd.Stdin, cmd.Stdout, cmd.Stderr = os.Stdin, os.Stdout, os.Stderr

	return cmd.Run()
}

Passthrough runs name in dir wired straight to this process's streams. A pager, an editor and `gh --web` all want the terminal, not a buffer.

var Pipe = func(ctx context.Context, dir, input, name string, args ...string) error {
	cmd := exec.CommandContext(ctx, name, args...)
	cmd.Dir = dir
	cmd.Stdin = strings.NewReader(input)
	cmd.Stdout, cmd.Stderr = os.Stdout, os.Stderr

	return cmd.Run()
}

Pipe runs name with input on its stdin and this process's terminal on its output - what a pager needs, and the one case where f10 both holds the text and wants someone else to display it.