Check yourself some shell-sources.

If interested, you can check the plain old /bin/sh signal handling in the source code here.

I am trying to understand how CTRL+C terminates a child but not a parent process. I see this behavior in some script shells like bash where you can start some long-running process and then terminate it by entering CTRL-C and the control returns to the shell. Could you explain how does it work and in particular why isn't the parent (shell) process terminated? Does the shell have to do some special handling of CTRL+C event and if yes what exactly does it do?

However, banning him opens a very dangerous precedent, making the US more like a dictatorship... more like China. Also it's not effective. Those who were silenced will only have more motivation, and the risk of terrorism is greatly increased. The people must decide what is true. Not big companies. Individuals must be able to express their beliefs. Bot accounts must be banned, but real individuals must not. If you think a group of people is a bunch of idiots who believe fake news, then, tough, that's democracy for you. Maybe it means that your government is not investing enough in education and welfare to properly educate and give hope to those people.

I oppose the banning of Donald Trump and his non-violent believers/content from social media platforms such as Facebook Twitter, YouTube and Amazon. I feel (irrationally?) Trump is arrogant and disgusting as a person. I like some of his anti-CCP policies, but not sure I'd vote for him. The "USA First" stance is particularly damaging as it scares USA allies away. I don't think there's enough evidence for the electoral fraud allegations, but I haven't researched the court cases extensively. However, banning him opens a very dangerous precedent, making the US more like a dictatorship... more like China. Also it's not effective. Those who were silenced will only have more motivation, and the risk of terrorism is greatly increased. The people must decide what is true. Not big companies. Individuals must be able to express their beliefs. Bot accounts must be banned, but real individuals must not. If you think a group of people is a bunch of idiots who believe fake news, then, tough, that's democracy for you. Maybe it means that your government is not investing enough in education and welfare to properly educate and give hope to those people. I'm against violence.

AWS can even terminate or suspend its agreement with a customer immediately under certain circumstances as it did in 2010 with Wikileaks, pointing to violations of AWS’ terms of service.

The swiftness with which Amazon acted shouldn’t come as a shock. Companies have been disclosing details about their deals with Amazon that warn of these kinds of sudden discontinuations for years.

The incident demonstrates a type of power that Amazon wields almost uniquely because so many companies rely on it to deliver computing and data storage.

Quit the program by sending a different signal to both processes, e.g. SIGQUIT with Ctrl + \.

PGID=$(ps opgid= "$PID") # get the Process Group ID

The CTRL-\ key sends a kill signal to the foreground job which, under normal circumstances, is guaranteed to terminate it. This signal cannot be captured by a process. However, this means the process cannot cleanup and is just summarily stopped. In some cases, a process can be stuck in a kernel wait state so this signal never reaches it. In that case, the process is unusable but cannot be killed.

This didn't work for me. Answering "y" somehow causes the script to finish immediately, rather than letting children continue sleeping. (Same thing if I make the signal handler function an empty no-op.) Does anyone know why it doesn't work for me or how to get it to work? It's as if the interrupt gets propagated to the child processes too so that it's no longer waiting for them.

Also, this code will fail if $$ is not the process group leader, such as when the script is run under strace. Since a call to setsid(2) is probably tricky from a shell script, one approach might be to ps and obtain the process group ID from that.

you really need #!/bin/sh -m for correct behavior of nested subshells. fg, bg, and wait wont work correctly otherwise

ps -o pid,pgid,stat,args

When your script starts a process, that child becomes a member of a process group with PGID equal to the PID of the parent process which is $$ in the parent shell.

To accomplish this, after starting the children (loop.sh) in the background, call wait, and upon receipt of the INT signal, kill the process group whose PGID equals your PID.

read -rep $'\nDo you wish to stop playing?(y/n)' yn

You also need job controlled -monitoring in your parent so it keep track of its children. wait, for example, only works at all with job control. -monitor mode is how shells interact with terminals.

You need a trap in loop.sh. Traps are cleared for every subshell started unless they are explicitly trap ''SIG ignored by the parent.

so again, what, precisely, is false? Do you deny that a Control+C goes to the foreground process group?

what, pray tell, is false in my examples? I am curious, so please be precise.

Remove your last "just in case" trap, and the script should work fine also with the EXIT traps. INT in the trap calling the cleanup should be the correct way to deal with the interrupts, however

How about just having all the output from point X be redirected to tee without having to repeat it everywhere and mess with all the sub-shells and execs

exec > >(exec tee -a $logfile) 2>&1

Can you be more specific about the "weird version of bash" ? In some situations (when run as /bin/sh) it runs n Posix compatibility mode ... If this is the case add set +o posix prior to exec

The idea of the script is this: most of the important logic runs in a subshell which is piped through tee and to a logfile, so I don't have to tee every single line of the main logic to get it all logged.

The rsync and sleep commands (the sleep is just an example) are run through exec to prevent the creation of zombie processes if I kill the parent script while they're running, and each potentially-long-running command is wrapped in its own subshell so that when exec finishes, it won't terminate the whole script.

The parentheses always start a subshell. What's happening is that bash detects that sleep 5 is the last command executed by that subshell, so it calls exec instead of fork+exec. The sleep command replaces the subshell in the same process.

Help defend Monica from defamation! Stack Overflow, Inc. must repair the damage caused by their libel against Monica Cellio, cooperate with the community, be willing to talk, treat users with respect, learn about the world outside the United States, open the governance of the sites.

There's a bash debugger, bashdb, which is an installable package on many distros. It uses bash's built-in extended debugging mode (shopt -s extdebug).

ps --forest -o pid,tty,stat,time,cmd -g $(ps -o sid= -p 2795)

To get all the processes spawned by a process the whole tree needs to be built. I used awk for that. At first it builds a hash array to contain all PID => ,child,child... . At the end it calls a recursive function to extract all the child processes of a given process. The result is passed to another ps to format the result.

This is in fact where I started, but this gives me all processes, which is exactly what I don't want.

time run_with_timeout 3 sleep_and_exit 1 7; echo $?

# Usage: run_with_timeout N cmd args... # or: run_with_timeout cmd args... # In the second case, cmd cannot be a number and the timeout will be 10 seconds. run_with_timeout () { local time=10 if [[ $1 =~ ^[0-9]+$ ]]; then time=$1; shift; fi # Run in a subshell to avoid job control messages ( "$@" & child=$! # Avoid default notification in non-interactive shell for SIGTERM trap -- "" SIGTERM ( sleep $time kill $child 2> /dev/null ) & wait $child ) }

Personally, I prefer signalling an error for invalid values

it propagates (Option -p) the returnlevel ($?) so you may use it for your purpose.

if the process does not react on a normal kill, you may want to add an additional kill -9 a few seconds afterwards.

A “warning” signal is sent first, then, after a timeout, a “kill” signal, similar to the way init(8) operates on shutdown.

We can ask timeout to try to stop the program using SIGTERM, and to only send in SIGKILL if SIGTERM didn’t work. To do this, we use the -k (kill after) option. The -k option requires a time value as a parameter.

if you just want to add timeout as an additional option for the entire existing script, you can make it test for the timeout-option, and then make it call it self recursively without that option.

timeout_child () { trap -- "" SIGTERM; child=$!; timeout=$1; ( sleep $timeout; kill $child; ) & wait $child; } And the usage: ( while true; do echo -n .; sleep 0.1; done) & timeout_child 2

You might be confused because echo is both a shell built-in and a separate command.

i dont know why everyone wants to **** on everything that is not a "AAA" game, its not in its perfect state, but far from deserve a 3, i will give it a 9 so it counters the "just hate

If any of the inputs are invalid, #execute won't be run.

Grouped inputs It can be convenient to apply the same options to a bunch of inputs. One common use case is making many inputs optional. Instead of setting default: nil on each one of them, you can use with_options to reduce duplication.

# User fields
string :name
integer :age
date :birthday, default: nil

# Food preferences
array :pizza_toppings
boolean :wants_cake, default: nil

# Fields that are required
string :name
integer :age
array :pizza_toppings

# Fields that are optional
with_options default: nil do
  date :birthday
  boolean :wants_cake
end

There are times where it is useful to know whether a value was passed to run or the result of a filter default. In particular, it is useful when nil is an acceptable value.

main > h = {key_with_nil_value: nil}
=> {:key_with_nil_value=>nil}

main > h[:key_with_nil_value]
=> nil

main > h[:missing_key]  # this would be undefined in JavaScript (a useful distinction) rather than null, but in Ruby it's indistinguishable from the case where a nil value was actually explicitly _supplied_ by the caller/user
=> nil

# so we have to check for "missingness" ("undefinedness"?) differently in Ruby

main > h.key?(:key_with_nil_value)
=> true

main > h.key?(:missing_key)
=> false

When you run this interaction, two things will happen. First ActiveInteraction will type check your inputs. Then ActiveModel will validate them. If both of those are happy, it will be executed.

outcome.valid?

if outcome.success?

compose(Add, x: x, y: 3)

Add.run(x: x, y: 3)

Other filters will ignore blocks when given to them.

Filters

If you have value objects or you would like to build one object from another, you can use the converter option. It is only called if the value provided is not an instance of the class or one of its subclasses.

account.first_name = first_name if first_name.present? account.last_name = last_name if last_name.present?

presence: true, unless: 'first_name.nil?'

It requires an account to update, but the other inputs are optional. If they're missing, it'll ignore those attributes. If they're present, it'll update them.

def edit account = find_account! @account = UpdateAccount.new( account: account, first_name: account.first_name, last_name: account.last_name) end

In this simple example, the destroy interaction doesn't do much. It's not clear that you gain anything by putting it in an interaction.

Note that we have to pass a hash to .run. Passing nil is an error.

params.fetch(:account, {})

params[:account]

The value given to the default option will also be found.

Use the desc option to provide human-readable descriptions of filters. You should prefer these to comments because they can be used to generate documentation.

Lambda defaults are evaluated in the context of the interaction, so you can use the values of other inputs in them.

Setting it to a lambda will lazily set the default value for that input.

hash :with_defaults, default: {} do boolean :likes_cookies, default: true end

By default, hashes remove any keys that aren't given as nested filters. To allow all hash keys, set strip: false. In general we don't recommend doing this, but it's sometimes necessary.

Record filters allow you to require an instance of a particular class (or one of its subclasses) or a value that can be used to locate an instance of the object. If the value does not match, it will call find on the class of the record. This is particularly useful when working with ActiveRecord objects.

You can also create an anonymous interface on the fly by passing the methods option.

ActiveInteraction plays nicely with Rails. You can use interactions to handle your business logic instead of models or controllers.

> RecordInteraction.run!(encoding: 'ascii') => #<Encoding:US-ASCII>

main > Encoding.find('ascii')
=> #<Encoding:US-ASCII>

ActiveInteraction type checks your inputs. Often you'll want more than that. For instance, you may want an input to be a string with at least one non-whitespace character. Instead of writing your own validation for that, you can use validations from ActiveModel. These validations aren't provided by ActiveInteraction. They're from ActiveModel. You can also use any custom validations you wrote yourself in your interactions.

Since interactions behave like ActiveModels, we can use ActiveModel validations with them.

If ActiveModel deals with your nouns, then ActiveInteraction handles your verbs.

The outcome returned by .run can be used in forms as though it were an ActiveModel object.

You can also create a form object by calling .new on the interaction.

ActiveInteraction also supports merging errors. This is useful if you want to delegate validation to some other object. For example, if you have an interaction that updates a record, you might want that record to validate itself. By using the #merge! helper on errors, you can do exactly that.

ActiveInteraction provides detailed errors for easier introspection and testing of errors. Detailed errors improve on regular errors by adding a symbol that represents the type of error that has occurred.

Since we're using an interaction, we don't need strong parameters. The interaction will ignore any inputs that weren't defined by filters. So you can forget about params.require and params.permit because interactions handle that for you.

Inside #execute, we merge errors. This is a convenient way to move errors from one object to another.

Note that it's perfectly fine to add errors during execution. Not all errors have to come from type checking or validation.

Inside the interaction, we could use #find instead of #find_by_id. That way we wouldn't need the #find_account! helper method in the controller because the error would bubble all the way up. However, you should try to avoid raising errors from interactions. If you do, you'll have to deal with raised exceptions as well as the validity of the outcome.

Why is all this interaction code better? Two reasons: One, you can reuse the FindAccount interaction in other places, like your API controller or a Resque task. And two, if you want to change how accounts are found, you only have to change one place.

This probably looks a little different than you're used to. Rails commonly handles this with a before_filter that sets the @account instance variable.

For this one we'll define a helper method to handle raising the correct errors. We have to do this because calling .run! would raise an ActiveInteraction::InvalidInteractionError instead of an ActiveRecord::RecordNotFound. That means Rails would render a 500 instead of a 404.

value returned from #execute

By convention, we call this an outcome

Call .run on your interaction to execute it.

It's an implementation of the command pattern in Ruby.

The problem is that you what you want is actually not de-structuring at all. You’re trying to go from 'arg1', { hash2: 'bar', hash3: 'baz' }, { hash1: 'foo' } (remember that 'arg1', foo: 'bar' is just shorthand for 'arg1', { foo: 'bar' }) to 'arg1', { hash1: 'foo', hash2: 'bar', hash3: 'baz' } which is, by definition, merging (note how the surrounding structure—the hash—is still there). Whereas de-structuring goes from 'arg1', [1, 2, 3] to 'arg1', 1, 2, 3

{a: 1, b: 2, c: 3, d: 4} => {a:, b:, **rest} # a == 1, b == 2, rest == {:c=>3, :d=>4}

{a, b, ...rest} = {a: 1, b: 2, c: 3, d: 4}

You can rescue at the method level, but more likely you’d want to rescue at the statement level.

In Ruby 3 we now have a “rightward assignment” operator. This flips the script and lets you write an expression before assigning it to a variable. So instead of x = :y, you can write :y => x

(Yay for the hashrocket resurgence!)

we’re going to look how improved pattern matching and rightward assignment make it possible to “destructure” hashes and arrays in Ruby 3—much like how you’d accomplish it in, say, JavaScript

Please, do not buy this. I am really tired of "games" that are given critical praise because its cool to praise or because its political correct to do. I will break up my review in points so its clear why I dislike this "game" : 1) This is not a game. This is a short story, like an interactive book. 2) This game is so short, that I completed it in a 3 hour bus ride. It was boring. 3) Its a story of a girl that have to take the reigns of her life after divorce. WOMAN EMPOWERMENT. Now you know why this game is rated so highly 4) This is a MOBILE GAME. I paid $3 to play on an iphone (after watching a gaming channel give it GOTY contender. Needless to say, I never watched that gaming channel again). I FELT I WAS ROBBED OF TIME AND $3. Imagine how much I hated this game to feel like I was robbed even though it costed me only $3. 5) This game costs $7 on the eshop. You could buy CELESTE for $9 on sale on the Eshop. That is a great game. I recently bought Hollow Knight for $7 on Playstation. This interactive novel should not be sold as a game. Period. It is a waste of time and money.

That’s it, plain and simple. But if you want the legalese version, dive into it here.

What we do collect:The translated words you encounter so that we know what words you are exposed to and can serve up appropriate vocabulary quizzes.Any vocabulary quizzes you see and the results of those quizzes so that we can keep track of how well you know each vocabulary concept.Anonymized (not linked to anyone's particular account) web page URLs, whether translations show up on them, and whether any bugs or errors occur on those pages so that we can better detect any broad issues affecting our user base.

Honey does not track your search engine history, emails, or your browsing on any site that is not a retail website (a site where you can shop and make a purchase). When you are on a pre-approved retail site, to help you save money, Honey will collect information about that site that lets us know which coupons and promos to find for you. We may also collect information about pricing and availability of items, which we can share with the rest of the Honey community.

For example, a real estate agentCommercial Real Estate BrokerA commercial real estate broker is a middleman between sellers and buyers of commercial real estate, who helps clients sell, lease, or purchase commercial real estate. A commercial real estate broker has the freedom to work either as an independent agent, or as a member of a commercial real estate brokerage firm. with an established network of colleagues for contacting potential home buyers, in addition to a broad range of market information and advertising outlets. Wholesalers include the middlemen between manufacturers, producers, and retailers. The retailers themselves are the middlemen between wholesalers and the end customers.

Instead of modifying /usr/share/applications/google-chrome.desktop, the file can be copied into ~/.local/share/applications/google-chrome.desktop and modified without root access. This file will take precedence over the global desktop file.

This solution also works for chromium-browser.

thanks for the quick reply

array :translations do hash do string :locale string :name end end array inputs can only have one input nested underneath them. This is because every element of the array must be the same type. And the inputs nested inside arrays cannot have names because they would never be used.

Almost always form objects wrap existing model or two.

Nevermind, I use now reform-rails

@adisos if reform-rails will not match, I suggest to use: https://github.com/orgsync/active_interaction I've switched to it after reform-rails as it was not fully detached from the activerecord, code is a bit hacky and complex to modify, and in overall reform not so flexible as active_interaction. It has multiple params as well: https://github.com/orgsync/active_interaction/blob/master/spec/active_interaction/modules/input_processor_spec.rb#L41

you mean Action Form, right?

added question and removed question labels

(To clarify, I'm not personally needing / waiting on this change (not currently anyway). I was just looking at all the open issues in this project while deciding whether I should start using ActiveIntegration in my project...)

Now that v4 is released, maybe we can look again into merging this?

Any idea @AaronLasseigne if this is mergeable?

This is a breaking change so it'll have to go into a major release. I was working on a v4 release but it's too much. I think I'm going to pair it back and we can add this to the new v4. When I have that ready, I'll rebase the merge onto that branch.

pair

For now I've worked around this by putting all the key-value pairs into an array before passing them into the interaction, then re-building the hash inside the interaction. It works, but it requires some extra code

You can use it by allowing a hash with arbitrary keys, but that loses type-safety one that object.

No one has requested it before so it's certainly not something we're planning to add.

I'm sure there will be a few other people out there who eventually want something like this, since Interactions are actually a great fit for enforcing consistency in data structures when working with a schemaless NoSQL store, but obviously it's still a bit of a niche audience.

To give a little more context, structures like this often come up in my work when dealing with NoSQL datastores, especially ones that rely heavily on JSON, like Firebase, where a records unique ID isn't part of the record itself, just a key that points to it. I think most Ruby/Rails projects tend towards use cases where these sort of datastores aren't appropriate/necessary, so it makes sense that this wouldn't come up as quickly as other structures.

Thanks, I'll continue leaning on the array workaround for my use case then.

I had to use something like this: occupancy.errors.messages.each do |column, messages| messages.each { |m| errors.add(column, m) } end

I have a Post object that has_one :schedule with accepts_nested_attributes_for :schedule as well. The latter method sets autosave: true, which unfortunately has the effect of hoisting up errors into the parent object so that the errors object on Post looks like this: (byebug) post.errors.details {:"schedule.publish_at"=>[{:error=>:blank}]}

The naughty pseudo-attribute name with the dot in it

The Rails side doesn't support any handling of these nested attribute names in the error yet it generates them from somewhere.

I bought this software mainly for the multiple camera capture. I upgraded to the Pinnacle Studio 24 Ultimate.The Ultimate version still restricts how many cameras can be added.To add more cameras requires purchasing another upgrade.Their 'Ultimate' version isn't the ultimate if they are still holding back features.

There is an evil genius lurking around in this software, playing withyour emotions and your work. This monster wants to sell its product by any means,even if it means shutting down your work at a crucial moment so that you would run to buy the next version. Update this and update that and buy! buy! buy!For your own wellbeing, don't buy it.

Can't have a steam library without MMX.

I feel like I should've paid more for this masterpiece.

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I don't think seeing it in Rails PRs naturally means we should do it blankly. Put it another way, what's the justification in those PRs for doing it?

The rationale is that it's actually clearer to eager initialize. You don't need to worry about timing/concurrency that way. Lazy init is inherently more complex than eager init, so there should be a reason to choose lazy over eager rather than the other way around.

I like the clarity of this approach instead of stuffing it in initialize.

collect_errors_from(model) vs. collect_errors_from(form) where form is one of the sub forms of the form (yes, I don't like that either).

The main realization came when I figured out that the main_model was just another association. This means we can move a lot of logic to just that class and reason about it a lot better.

But ActiveModel doesn't support out of the box argument parsing, e.g. having a datetime attribute be a datetime attribute and a boolean attribute be a boolean attribute.

class FormsController < ApplicationController class SearchForm < ActiveModel::Form

support round-tripping (assigning the submitted params again)

ActiveModel::Form happened because the "tableless model" presented in RailsCast 219 wasn't as powerful as the "real deal" from RailsCast 193.

def initialize(attributes=nil) self.assign_attributes(attributes) end

# Set the model name to change the field names generated by the Rails form helpers def self.model_name=(name) @_model_name = ActiveModel::Name.new(self, nil, name) end

Teaching is my passion

It is difficult to come up with content that is not extracted from a real application. Manufacturing scenarios to see if ideas have practical application turned out to be an exhasting and time consuming process.

my transition to working on RailsCasts full time is the primary cause for me burning out.

The great thing about working with reinteractive is you get to work directly with the developers, which is a huge plus. As a technical founder, I find proxying through a project manager adds unnecessary layers of complexity and creates opportunity for human error.

Download this free e-book to learn how.

You provide the vision, we'll handle the rocket science!

So how are we going to create a model that doesn’t have a database table behind it? There are several potential solutions including various plugins but we’re going to use the method described in an entry on the Code Tunes blog. This shows a techinque that involves overriding a couple of methods in an ActiveRecord model and then manually defining the columns in the model file rather than in the database table. In our Recommendation model we’ll add in the two overridden methods and then use the column class method to define the columns in a similar way to how they’re defined in a migration file.

We could quite easily create a model class that isn’t based on ActiveRecord and have it work as Rails is quite decoupled from ActiveRecord, but there are advantages to keeping our model class inheriting from ActiveRecord.

Examples of different ways of defining forms

Bureaucrat doesn't define save

Scrivener is Bureaucrat's little brother. It draws all the inspiration from it and its features are a subset of Bureaucrat's.

The assert method is used by all the other assertions. It pushes the second parameter to the list of errors if the first parameter evaluates to false or nil.

Read about the motivation to understand why this separation of concerns is important.

or use Github's discontinued Rubygems server

Unfortunately the widespread adoption of this practice led to a huge number of orphaned gems that usually have only a single or at most a handful of releases. Additionally these forked gems often retained their upstream github source code url, so on the Ruby Toolbox these forks receive a high popularity ranking.

As a result, dry-types, dry-struct and dry-schema were born. These projects should be considered as virtus' successors, with better separation of concerns and better features.

Uses

A sample UML class and sequence diagram for the Command design pattern.

The central ideas of this design pattern closely mirror the semantics of first-class functions and higher-order functions in functional programming languages. Specifically, the invoker object is a higher-order function of which the command object is a first-class argument.

A sequence diagram shows object interactions arranged in time sequence.

For the usage in society, see Second-class citizen.

In programming language design, a first-class citizen (also type, object, entity, or value) in a given programming language is an entity which supports all the operations generally available to other entities. These operations typically include being passed as an argument, returned from a function, modified, and assigned to a variable.

In computer science, a programming language is said to have first-class functions if it treats functions as first-class citizens.

DISCLAIMER: This project is an experiment and should not be used in applications.

Set your models free from the accepts_nested_attributes_for helper. Action Form provides an object-oriented approach to represent your forms by building a form object, rather than relying on Active Record internals for doing this.

describe '.validate(context, filters, inputs)' do let(:inputs) { {} } let(:filter) { ActiveInteraction::Filter.new(:name, {}) } let(:interaction) do

Take 3, Previously attempted in 2012 (#8189) and 2015 (#19709). This new version uses ActiveModel Attributes API.

Another recent attempt: #35246

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.

rafaelfranca closed this on Feb 27, 2018