End Of The CLI? Or Just The Start?


Windows 8.1 Update 1 launches today. The latest chapter in Microsoft’s newest OS includes a new feature people been asking for since release: the Start Menu. The biggest single UI change in Windows 8 was the removal of the familiar Start button in favor of a combined dashboard / Start screen. While the new screen is much better for touch devices, the desktop population has been screaming for the return of the Start Menu. Windows 8.1 brought the button back, although it only linked to the Start screen. Update 1 promises to add functionality to the button once more. As I thought about it, I realized there are parallels here that we in the networking world can learn as well.

Some very smart people out there, like Colin McNamara (@ColinMcNamara) and Matt Oswalt (@Mierdin) have been talking about the end of the command line interface (CLI). With the advent of programmable networks and API-driven configuration the CLI is archaic and unnecessary, or so the argument goes. Yet, there is a very strong contingent of the networking world that is clinging to the comfortable glow of a terminal screen and 80-column text entry.

Command The Line

API-driven interfaces provide flexibility that we can’t hope to match in a human interface. There is no doubt that a large portion of the configuration of future devices will be done via API call or some sort of centralized interface that programs the end device automatically. Yet, as I’ve said before, engineers don’t like have visibility into a system. Getting rid of the CLI for the sake of streamlining a device is a bad idea.

I’ve worked with many devices that don’t have a CLI. Cisco Catalyst Express switches leap immediately to mind. Other devices, like the Cisco UC500 SMB phone system, have a CLI but use of it is discouraged. In face, when you configure the UC500 using the CLI, you start getting warnings about not being able to use the GUI tool any longer. Yet there are functions that are only visible through the CLI.


Will the programmable networking world will make the same mistake Microsoft did with Windows 8? Even a token CLI is better than cutting it out entirely. Programmable networking will allow all kinds of neat tricks. For instance, we can present a Cisco-like CLI for one group of users and a Juniper-like CLI for a different group that both accomplish the same results. We don’t need to have these CLIs sitting around resident memory. We should be able to generate them on the fly or call the appropriate interfaces from a centralized library. Extensibility, even in the archaic interface of last resort.

If all our talk revolves around the removal of the tool people have been using for decades to program devices you will make enemies quickly. The talk needs to shift from the death of CLI and more toward the advantages gained through adding API interfaces to your programming. Even if our interface into calling those APIs looks similar to a comfortable CLI, you’re going to win more converts up front if you give them something they recognize as a transition mechanism.

Tom’s Take

Microsoft bit off more than they could chew when they exiled the Start Menu to the same pile as DOSShell and Microsoft Bob. People have spent almost 20 years humming the Rolling Stones’ “Start Me Up” as they click on that menu. Microsoft drove users to this approach. To pull it out from under them all at once with no transition plan made for unhappy users. Networking advocates need to be just as cognizant of the fact that we’re headed down the same path. We need to provide transition options for the die-hard engineers out there so they can learn how to program devices via non-traditional interfaces. If we try to make them quit cold turkey you can be sure the Start Menu discussion will pale in comparison.

3 thoughts on “End Of The CLI? Or Just The Start?

  1. I’d say Microsoft agree with you: it’s only recently that they’ve provided a decent CLI themselves in PowerShell.

  2. I see the new world of networking as just adding new options. I don’t think the CLI will go away. API’s will simply be an additional way to interact with and configure network devices. Time will tell.

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