> Also, has anyone though of how mind-numbingly wasteful solar fusion is? All that energy, and only a tiny fraction makes it to Earth with the rest getting dumped wastefully into space. Seems like an area that's ripe for disruption by a startup.
That energy can be captured by a Dyson sphere:
> A Dyson sphere is a hypothetical megastructure that encompasses a star and captures a large percentage of its solar power output
Is this a bad thing? Investing a lot into safety measures to avoid catastrophes seems better than investing significantly less because we assume is safe.
Could you elaborate on why this investment is an argument against nuclear?
I once talked to people that worked at Angra Nuclear Power Plant in Brazil and they said the real danger is actually the spent nuclear fuel. The power plant itself is safe due to many redundant safety measures, continuous tests and monitoring. I don't have a source for this, and don't take my words for absolute truth, I'm not an expert in the subject.
> kept from harming us by a large crew of skilled people
I'm glad to hear people working with nuclear are skilled ;) I assume people working in solar/wind/hydro are also skilled at their craft. And I'm sure you didn't imply that, maybe the phrasing wasn't the best?
>Could you elaborate on why this investment is an argument against nuclear?
It is not an argument against nuclear, it is an argument against the claim that nuclear is safe.
If something requires a large staff of skilled workers and very expensive equipment in order to prevent harmful effects, it is of course not safe - wouldn't you agree?
Solar and wind require skilled people too for sure, but not in order to prevent a catastrophe, which was my point here.
The type of catastrophe that solar and wind need to prevent are "There's no sun/wind for more days than we planned for" which absolutely can be devastating and no amount of skilled people can fix
>The type of catastrophe that solar and wind need to prevent are "There's no sun/wind for more days than we planned for" which absolutely can be devastating
Absolutely, and with renewables that's part of the consideration from the start since everyone is well aware of it.
What you describe is in fact one of the major downsides to nuclear, since they generate so much energy in one point of failure.
Having a (ahem) redundant array of inexpensive devices generating power is much less likely to suffer abrupt and large losses such as the one europe suffered just last week, when their largest reactor went offline for a few days. https://yle.fi/a/74-20061159
Brazil abolished daytime change a couple of years ago. Our time is the same all year, no more +1 and then -1 hour.
It was mess on the day there should a change, many people arrived on their appointments one hour before or later. Many automatic systems changed their time, different clocks at home reported different hours.
This chaos lasted one morning. After some time, nobody now complains about not having it. Many people don't remember about the change anymore. The only people that complains about daylight change are the ones that work with people from countries that have that.
Abolishing daytime change is not the same as adopting an "universal" (country-like?) timezone, but shows that it is _possible_ to do on a "big country spanning a lot of latitude as well as longitude and tens of millions on wildly different work and sleep schedules".
Maybe the main issue is that many people fear change? (Which is quite "funny", as winter/summer time is a change in time...)
One of those left out features is `sudoedit` or `sudo -e`. I use this a lot when editing files in /etc or any file that my user does not have permissions. The flag first copies the file to a temporary location with permissions for my user to edit, then opens my text editor (defined via $SUDO_EDITOR env var) as _my user_, without any sudo permissions. After I close the editor, the file is copied back with the original permissions only if there were any changes.
The cool thing is running the editor via my user, which loads my user's configuration/plugins, instead of the root user's.
This would be a great use case for a capability security model. Essentially what you really want is the sudo command to acquire a temporary capability token to edit that specific file. Then run your editor and pass it the capability. (And revoke the capability when the editor process closes).
It’s a pity this isn’t more straight forward to implement on Linux.
Are there no overwrite/seek bugs in Unix that could be exploited in that case? It seems to me like only using sudo for a cp command would reduce the attack surface.
I’d certainly hope not. A capability based security system in an OS is only secure if it doesn’t have bugs. Just like most security-critical software.
However, I’m not sure that Linux is capable of masquerading as a general purpose capability based operating system. I think it’s missing a bunch of APIs.
It's doable by opening the file in a privileged process (sudo) and passing the file descriptor to a non-privileged process.
Maybe one could make a sudoedit that opens a file in sudo process and then spawns a non-privileged editor process which inherits the file descriptor and is given the /dev/fd/ path on the command line, so it stays none the wiser about the whole process.
Sounds like a bit of recipe for accidentally handing access to an unintended privileged fd through inheritance (ignoring the /dev/fd one) such that a compromised unprivileged SUDO_EDITOR value gives you sudo access. Maybe not likely, but I’d really be hesitant about any feature that relies on implicit fd inheritance…
Another option could be to open a UNIX socket in the privileged sudo process, spawn an unprivileged child process 'shim' that connects to that socket, and then the sudo process can pass the file descriptor over the socket. Since the child shim is 'clean', it should have nothing more than stdin/out/err open, plus now this passed FD. Then the shim can spawn the target program and allow it to inherit just the passed FD.
I think the larger issue is that I doubt many (if any?) editors allow opening a file via an inherited file descriptor! I guess some will read stdin (the shim could close stdin and then dup2() it into its place), but then there's no way to save the file back when finished.
Close all other fds between fork and exec then (you can look at the code of base::LaunchProcess in Chromium for an example). It’s a minuscule amount of code to audit compared to XDG portals. And it’s backwards-compatible with decades of unix programs.
For a more complicated solution: spawn a zygote process early with a unix socket which you’ll use to send the fd later. Zygote at start drops provileges. When it receives the fd, it closes the socket and execs the editor.
I’m not saying it’s not possible to do correctly. But do you not agree that the first is hard to correctly (can overlook an fd) while the latter is a lot of complexity?
There is the CLOEXEC flag which is the intended way to manage this but it’s not the default and you have to be diligent about setting it which again carries its own set of challenges.
What you’d really want is CLOEXEC implicitly on all fds and having to explicitly opt in for fd inheritance.
So now any program that's running as your user, even your browser, can edit any file you edit with sudo. It just has to watch for your editor to quit and win a race with sudo to modify the file before sudo reads it.
It is a little less useful if the file is not readable by your user, and once you authenticate anything within your vim can also silently run other sudo commands since on most distros sudo remembers the autnentication for a while.
Now that I think of it, not sure how sudoedit behaves wrt this cached auth.
That makes your editor run as root, which is a bad idea for many reasons (aside from security, any mistake now has the potential mess with the whole system).
I really liked the calculus book by Swokowski. The books starts with a revision of the requirements to start learning derivatives, has sections dedicated to applications of that and then goes on to integrals, analytical geometry and differential equations. It will keep you entertained for months.
That energy can be captured by a Dyson sphere:
> A Dyson sphere is a hypothetical megastructure that encompasses a star and captures a large percentage of its solar power output
- https://en.wikipedia.org/wiki/Dyson_sphere