etcdctl/ctlv2/command/update_command.go
func NewUpdateCommand() cli.Command {
	return cli.Command{
		Name:      "update",
		Usage:     "update an existing key with a given value",
		ArgsUsage: "<key> <value>",
		Flags: []cli.Flag{
			cli.IntFlag{Name: "ttl", Value: 0, Usage: "key time-to-live in seconds"},
		},
		Action: func(c *cli.Context) error {
			updateCommandFunc(c, mustNewKeyAPI(c))
			return nil
		},
	}
}
func NewUpdateCommand() cli.Command {
	return cli.Command{
		Name:      "update",
		Usage:     "update an existing key with a given value",
		ArgsUsage: "<key> <value>",
		Flags: []cli.Flag{
			cli.IntFlag{Name: "ttl", Value: 0, Usage: "key time-to-live in seconds"},
		},
		Action: func(c *cli.Context) error {
			updateCommandFunc(c, mustNewKeyAPI(c))
			return nil
		},
	}
}
// NewUpdateCommand returns the CLI command for "update".