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In the Beginning Was the Command Line (1999)

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412 points conanxin | 1 comments | 27 Jul 24 06:25 UTC | HN request time: 0s | source
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pavlov ◴[27 Jul 24 09:56 UTC] No.41085505[source]▶
The CLI has a massive blind spot in today’s operating systems: it knows nothing useful about events.

Yet events are the primary way anything happens on a computer, whether it’s a user system or a server.

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1. dredmorbius ◴[28 Jul 24 01:50 UTC] No.41090695[source]▶
That's the specific hole which Expect fills for scripting:

<https://en.wikipedia.org/wiki/Expect>

Much of modern operating systems is events-based and relies on polling for specific actions, devices connecting / disconnecting, etc. Linux device management is based on this, for example. There are numerous scripts which fire as a service is enabled or disabled (networking "ifup" and "ifdown" scripts, for example), or services are started / stopped. Systemd extends these capabilities markedly.

And of course there's a whole slew of conditional processing, beginning with init scripts, [], test, &&, ||, and specific conditional logic within shells, scripting, and programming languages.