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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 compu

by pavlov 2y ago

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.

fock 2y ago
huh? DBUS is very much a thing and has CLI-tooling?
nonrandomstring 2y ago
Annoying though it may be, you can run a program in the background that can write to your open terminal. Just in userspace you have; dmesg -w tail -f /var/log/messages There's also dbus to monitor on Linux systems and a lot of kernel hook tricks you can use to get a message pop up if an event happens. Because it gets annoying to have a process splurge notification stuff to a term you are working in, that's why you have info-bars which many terminal emulators support.
skydhash 2y ago
In unix world, everything is a file, so you can poll the file waiting for something to happen. And there’s the whole signal thing and dbus exists.
- pavlov 2y ago
  Yeah, these are the event paradigms that I meant by “nothing useful.” Files are not a good abstraction for events. Signals are broken in many ways. And DBus is both extremely clunky to use and non-portable. There isn’t a built-in event paradigm similar to how streams and pipes are an integral part of the Unix-style CLI.
  - dandanua 2y ago
    > Files are not a good abstraction for events Why is that? On the low level everything is a state of electronic cells. Files address those cells in a suitable fashion. Modern programming abstractions such as async/await are very simple, but fail miserably if you need something really complex and efficient.
anthk 2y ago
You mean, like entr triggering commands?
johnklos 2y ago
I can't even understand this. How does the CLI relate to events? Are you saying that all servers secretly have an invisible GUI and handle events there? This just seems like an odd non sequitur.
dredmorbius 2y ago
That's the specific hole which Expect fills for scripting: <https://en.wikipedia.org/wiki/Expect 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.

by pavlov 2y ago

fock 2y ago

huh? DBUS is very much a thing and has CLI-tooling?

nonrandomstring 2y ago

Annoying though it may be, you can run a program in the background that can write to your open terminal. Just in userspace you have; dmesg -w tail -f /var/log/messages There's also dbus to monitor on Linux systems and a lot of kernel hook tricks you can use to get a message pop up if an event happens. Because it gets annoying to have a process splurge notification stuff to a term you are working in, that's why you have info-bars which many terminal emulators support.

skydhash 2y ago

In unix world, everything is a file, so you can poll the file waiting for something to happen. And there’s the whole signal thing and dbus exists.

pavlov 2y ago
Yeah, these are the event paradigms that I meant by “nothing useful.” Files are not a good abstraction for events. Signals are broken in many ways. And DBus is both extremely clunky to use and non-portable. There isn’t a built-in event paradigm similar to how streams and pipes are an integral part of the Unix-style CLI.
- dandanua 2y ago
  > Files are not a good abstraction for events Why is that? On the low level everything is a state of electronic cells. Files address those cells in a suitable fashion. Modern programming abstractions such as async/await are very simple, but fail miserably if you need something really complex and efficient.

anthk 2y ago

You mean, like entr triggering commands?

johnklos 2y ago

I can't even understand this. How does the CLI relate to events? Are you saying that all servers secretly have an invisible GUI and handle events there? This just seems like an odd non sequitur.

dredmorbius 2y ago

That's the specific hole which Expect fills for scripting: <https://en.wikipedia.org/wiki/Expect 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.