From whence the Command Line Interface?

I've taken typing ASCII strings into serial ports as a normal interaction for decades now. Sometimes the strings seemed like arcane incantations that made little sense to me, but seemed to do the right things (in the end) on the device that I was talking to. I've written programs and scripts that took input from a user (via a keyboard, serial port, and other inputs), and I learned to "sanitize the input", and how to parse it, and how to cough up an error if the input was something unexpected, or not in the format that I wanted.

Over the years, I've had to sift through manuals, and command-completion information screens, in order to be reminded what my options are, on this device, running that version of firmware. Mainly because it seems so familiar, overall, but the occasional command options, or the order of arguments, may have been changed.

Today, I was sifting the web, looking for information to configure the serial port settings on an Avocent CCM4850. It turns out that line had roots from Equinox, with a different command syntax from the Cyclades line (which was also absorbed into Avocent, many years ago). But It also looks like the command syntax used for Lantronix and others. And this is when I decided to write this article.

Earlier in this month, Cisco Networks announced it was going to sue Arista Networks (Cisco's announcement) over what looked like copying of their Command Line Interface structures (and a few other items). Arista posted a couple early responses (from the Legal Counsel and the CTO), and I'm curious to see where it goes, and what effect it may have on the decade-old networking company. But, part of the argument begs the question about whether you can protect your Command Line Interface syntax. Are some command lines intuitive (after decades of predecessors...), and are some "common" enough that they become open to the public domain? Would the market benefit if a vendor could lock-in a particular set of commands, while competitors had to find unique ways to configure the same settings?

It harkens me back to the days of the big re-write of the Point-to-Point (PPP) protocols in the IETF Request For Comments... there were only three RFCs then, and there was confusion among the companies trying to write compatible versions. Many companies (Microsoft, Novell, Telebit, Morningstar) were trying to work on vendor-specific adaptations, and some were trying to find a way to aggregate multiple modem links into one larger pipe. The rewrite moved us into 13 different, new RFCs, but they helped lay the groundwork for interoperability. The PPP Consortium grew monthly, as more vendors jumped aboard to make things work together. And many command strings started to look alike. A LOT alike! And, at the time, that seemed like a very good thing, since I didn't have to reference many manuals to get a link running.

So, today, I'm wondering what the downside is, if different network vendors can parse the same command line string to provision VLAN or Spanning Tree settings for a switchport. And what may happen in the Console Server world if a ruling comes out that vendors must have unique command line syntaxes. How many syntaxes would you want to support, or remember?

Happy New Year! I can hardly wait to see what's ahead.

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