3 ms·

> You could definitely write a build system in shell. In my opinion, "the job" is subjective and you shouldn't have to pick one tool for it. But I would prefer

> You could definitely write a build system in shell. In my opinion, "the job" is subjective and you shouldn't have to pick one tool for it. But I would prefer a simple one where I can see pretty much everything it's doing up front and not have to download source code or search through docs. You likewise have to read docs or the source to know what your shell is really doing. Or search through sysvinit docs to know which shell scripts it will run and when. I have to look up how to use shell conditionals every time, and it's extremely easy to get it subtly wrong such that it's not doing what you think it's doing. There are subtle distinctions between shell built-ins and programs of the same name, and it's very unclear in some cases which is being called. The shell is far from being a beautifully simple and transparent abstraction. Perhaps you know it too well to be able to appreciate this. The shell and sysvinit are abstractions over writing C programs that make POSIX library calls directly. It's all abstractions unless you are writing machine code directly, (and even then you have to read docs to know what the instructions really do). So given that we're all using abstractions, we ought to use the best ones; the one that gives us the most advantages and the fewest disadvantages given the problem we are trying to solve. The ones that have the greatest combination of simplicity, transparency, and expressiveness. If you want to make sure that only one copy of a program is running, is it a better fit to write a shell script that creates a pidfile, checks to make sure there's a running process that matches it, and that handles a million cases about how the two can fall out of sync? Or is it better to be able to express directly "I want one copy of this program running" and then let the abstraction handle the hard cases? You might say "well the shell script is easier to debug, because I wrote it and I understand it." Well of course, you always understand the things you wrote yourself. But if I had to debug either a pidfile-making shell script or a well-designed babysitter tool, I'll take the specific tool every time. If it's mature, it's also a lot less likely to have bugs and race conditions. > Debian picked up systemd because it was a popular decision, not because it was better. As far as i'm aware there was nothing broken in sysvinit that systemd fixed; there was just a vocal minority that wanted some new features and insisted it be shipped as default. I don't think you're very well-informed about this. Your claim of a "vocal minority" is particularly suspect, considering the decision was made by a vote of the technical committee. Though there was disagreement, almost no one was in favor of sysvinit. And the position paper in favor of systemd identifies specific things that are lacking in sysvinit: https://wiki.debian.org/Debate/initsystem/systemd https://wiki.debian.org/Debate/initsystem/systemd

peterwwillis 13y ago
What you're arguing for is essentially the difference between a shell script and a more complicated shell script [some tool designed to "express directly" what you want to do]. You ask, why wouldn't we use something more complicated if it does exactly what we want to do? Because unless you really need to do some exact thing, it adds unnecessary complexity which leads to many additional problems. And if you need the added functionality, you can always add a feature or use a pre-existing tool. Your debugging argument is bonkers. You claim shell scripting is too hard, then say it must be easy to troubleshoot a "well-designed babysitter tool", which requires WAY more domain-specific knowledge of debugging tools! If you don't know how to write bash scripts, you sure as hell aren't going to have an easy time figuring out why your package manager's borking on an update of openssl. Did you even read the executive summary of the position paper? "Systemd is becoming the de facto standard" .. "Systemd represents a leap in terms of functionality" .. "People are starting to expect this functionality [..] and missing it could [..] make Debian lose its purpose." They only want it because it has new features, and people are starting to expect it. It's a popularity contest, and systemd won.
- haberman 13y ago
  > What you're arguing for is essentially the difference between a shell script and a more complicated shell script You seem to have a really shell-script-centric view of the world, as if the shell is somehow a fundamental and "pure" tool, and everything else is a more complicated version of a shell script. What you are missing is that the shell is just another tool, and does an awful lot behind the scenes to achieve the functionality that appears "simple" to you. Bash is tens of thousands of lines of C and its manpage is hundreds of thousands of words. Using the shell is not "free", complexity-wise. The shell is a programming language, and not a particularly well-designed one at that. Shell script programming introduces its own peculiarities, and it is known not to scale in complexity very well. > Your debugging argument is bonkers. You claim shell scripting is too hard No, I claim that the shell is not a particularly simple tool. There is a difference. I write JIT compilers for fun. I don't shy away from things that are hard. But my brain has only so much room for uninteresting and arbitrary facts. The very pecular way that conditionals work in the Bourne Shell is not something my brain can be bothered to remember. > Did you even read the executive summary of the position paper? You have edited out precisely the parts that contradict your position: "It replaces the venerable SysV init with a clean and efficient design [...] It is better than existing alternatives for all of Debian’s current use cases." Yes, the momentum of systemd was clearly a factor, but your claim that it is only but a popularity contest is not a conclusion that a dispassionate observer would reach.

peterwwillis 13y ago

What you're arguing for is essentially the difference between a shell script and a more complicated shell script [some tool designed to "express directly" what you want to do]. You ask, why wouldn't we use something more complicated if it does exactly what we want to do? Because unless you really need to do some exact thing, it adds unnecessary complexity which leads to many additional problems. And if you need the added functionality, you can always add a feature or use a pre-existing tool. Your debugging argument is bonkers. You claim shell scripting is too hard, then say it must be easy to troubleshoot a "well-designed babysitter tool", which requires WAY more domain-specific knowledge of debugging tools! If you don't know how to write bash scripts, you sure as hell aren't going to have an easy time figuring out why your package manager's borking on an update of openssl. Did you even read the executive summary of the position paper? "Systemd is becoming the de facto standard" .. "Systemd represents a leap in terms of functionality" .. "People are starting to expect this functionality [..] and missing it could [..] make Debian lose its purpose." They only want it because it has new features, and people are starting to expect it. It's a popularity contest, and systemd won.

haberman 13y ago
> What you're arguing for is essentially the difference between a shell script and a more complicated shell script You seem to have a really shell-script-centric view of the world, as if the shell is somehow a fundamental and "pure" tool, and everything else is a more complicated version of a shell script. What you are missing is that the shell is just another tool, and does an awful lot behind the scenes to achieve the functionality that appears "simple" to you. Bash is tens of thousands of lines of C and its manpage is hundreds of thousands of words. Using the shell is not "free", complexity-wise. The shell is a programming language, and not a particularly well-designed one at that. Shell script programming introduces its own peculiarities, and it is known not to scale in complexity very well. > Your debugging argument is bonkers. You claim shell scripting is too hard No, I claim that the shell is not a particularly simple tool. There is a difference. I write JIT compilers for fun. I don't shy away from things that are hard. But my brain has only so much room for uninteresting and arbitrary facts. The very pecular way that conditionals work in the Bourne Shell is not something my brain can be bothered to remember. > Did you even read the executive summary of the position paper? You have edited out precisely the parts that contradict your position: "It replaces the venerable SysV init with a clean and efficient design [...] It is better than existing alternatives for all of Debian’s current use cases." Yes, the momentum of systemd was clearly a factor, but your claim that it is only but a popularity contest is not a conclusion that a dispassionate observer would reach.