Disable APT Cache in Debian

In the Debian system, the packages are normally installed through the apt package manager, which installs the packages from the official Debian repository. The packages installed through apt are moved to the cache directory and are managed inside the location ‘/var/cache/apt/archives’. The reason to put these files in the cached directory is to ensure that the next time you install a dependent package of an existing package, it won’t install the same package again; instead, it will pick up the package from this location. As time passes, the package loses its worthiness and the time will come when it won’t require any more on the system. Thus, it is a good practice to disable the apt cache on the Debian system, as this will help free up some space.

Follow this article’s detailed guidelines to disable apt cache in Debian.

How to Disable APT Cache in Debian

An easy step-by-step instruction to disable apt cache in Debian is given below:

Step 1: First, you must create a 00clean-cache-dir file on the Debian system through nano editor:

sudo nano /etc/apt/apt.conf.d/00clean-cache-dir

Step 2: Within the file, you must add the following line:

DPkg::Post-Invoke {"/bin/rm -f /var/cache/apt/archives/*.deb || true";};

Step 3: Then save the clean cache file using “CTRL+X”, add “Y” and enter to exit.

Step 4: Then you have to create another file with “00disbale-cache-files” name:

sudo nano 00disable-cache-files

Step 5: Within this file, add the following lines:

Dir::Cache::srcpkgcache "";

Dir::Cache::pkgcache "";

Step 6: Save this file using Step 3.

This will disable the apt cache on the Debian system.

Step 7: Now the apt cache is disabled now, it’s better to empty the ‘/var/cache/apt/archives’ directory on Debian using the following command:

sudo rm -rf /var/cache/apt/archives

Step 8 (Optional): Alternatively, it’s a good practice if you run the following command to delete the cache:

sudo apt clean --dry-run

Step 9 (Optional): Further you can also remove the cache files and directories through the following command:

sudo apt clean

Step 10 (Optional): Let’s clean the system by removing the cache file and directories using the following command.

sudo apt autoclean

Conclusion

The apt cache on Debian can be disabled easily by creating a clean cache file inside the /etc/apt/apt.conf.d/ location. Then create another file with disable cache in the home location. Save both these files to disable the apt cache on Debian. It’s better to remove cache files and directories through “rm -rf” command or some apt commands that are optional but good practice if you run them on the terminal.

Original article source at: https://linuxhint.com/

#debian #cache 

What is GEEK

Buddha Community

How to Install and Correct Dependencies Issues in Ubuntu

What is a Dependency?
A dependency is defined as a file, component, or software package that a program needs to work correctly. Almost every software package we install depends on another piece of code or software to work as expected. Because the overall theme of Linux has always been to have a program do one specific thing, and do it well, many software titles utilize other pieces of software to run correctly.

Introduction
Let’s review what dependencies are and why they are required. We all have, at one point or another, most certainly seen a message from our system when we were installing software regarding “missing dependencies.” This error denotes that a required part of the software package is outdated, unavailable or missing. Let’s review how to address those issues when we come across them on Ubuntu.

#tutorials #apt #apt-cache #apt-get #apt-mark #autoclean #autoremove #cache #clean #cleanall #component #dependencies #dependency errors #dpkg #file #linux #package #ppa #ppa-purge #purge #python #repository #showhold #software #ubuntu #unmet dependencies errors

Microsoft Exchange, Outlook Under Siege By APTs

New, sophisticated adversaries are switching up their tactics in exploiting enterprise-friendly platforms — most notably Microsoft Exchange, Outlook Web Access (OWA) and Outlook on the Web – in order to steal business credentials and other sensitive data.

Both Microsoft’s Exchange mail server and calendaring server and its Outlook personal information manager web app provide authentication services – and integration with other platforms – that researchers say are prime for attackers to leverage for launching attacks.

Accenture’s 2020 Cyber Threatscape report, released Monday, shed light on how actors are leveraging Exchange and OWA – and evolving their tactics to develop new malware families that target these services, or using new detection evasion techniques.

“Web-facing, data-intense systems and services that typically communicate externally can make it easier for adversaries to hide their traffic in the background noise, while authentication services could open up a credential-harvesting opportunity for cybercriminals,” according to Accenture researchers on Monday.

APTs Flock Exchange, OWA

One threat group that has been targeting Exchange and OWA is what researchers dub “BELUGASTURGEON” (aka Turla or Whitebear). Researchers say that this group operates from Russia, has been active for more than 10 years and is associated with numerous cyberattacks aimed at government agencies, foreign-policy research firms and think tanks across the globe.

The group is targeting these Microsoft services and using them as beachheads to hide traffic, relay commands, compromise e-mail, exfiltrate data and gather credentials for future espionage attacks, said researchers. For instance, they are manipulating legitimate traffic that’s traversing Exchange in order to relay commands or exfiltrate sensitive data.

“Hosts supporting Exchange and associated services frequently relay large volumes of data to external locations— representing a prime opportunity for malicious actors to hide their traffic within this background noise,” said researchers.

Another group, which researchers call SOURFACE (aka APT39 or Chafer), appears to have developed similar techniques to conceal malicious traffic, manipulating local firewalls and proxying traffic over non-standard ports using native commands, tools and functions, researchers said. Researchers said this group has been active since at least 2014 and is known for its cyberattacks on the oil and gas, communications, transportation and other industries in the Australia, Europe, Israel, Saudi Arabia, the U.S. and other regions.

In addition, threat groups are also creating new malware designed to specifically target Exchange and OWA. Researchers said they discovered several malicious files in the wild in 2019 that they assessed “with moderate confidence” were associated to a group called BLACKSTURGEON, used in targeting government and public sector orgs.

That includes a file that seemed like a version of the group’s customized version of the “RULER” tool, which is designed to abuse Microsoft Exchange services. This file exploits the CVE- 2017-11774 Outlook vulnerability, a security-feature bypass vulnerability that affects Microsoft Outlook and enables attackers to execute arbitrary commands, researchers said.

Other Services Under Attack

Cybercriminals are also targeting services that support Exchange and OWA. For instance, client-access servers (CAS), which handle all client connections to Exchange Server 2010 and Exchange 2013, typically operate in web-login portals for services including OWA. Attackers with access to CAS may be able to deploy capabilities to steal user login credentials, researchers said.

“Notably, an advanced persistent threat actor reportedly deployed web shells to harvest credentials from OWA users as they logged in,” they said.

The Windows Internet Information Services (IIS) platform, which supports OWA, is another increasing target. IIS is a web server software created by Microsoft for use with the Windows family. Researchers said they have observed SOURFACE, for instance, deploying custom Active Server Page Extended (ASPX) Web shells to IIS directories within the victim’s OWA environment. These web shells would include discrete file names, to resemble legitimate files on the victim’s system (for instance “login2.aspx” instead of “login.aspx”). And, to evade static detection, they typically contained limited functionality, often only file upload and download or command execution.

#cloud security #government #hacks #vulnerabilities #web security #accenture 2020 cyber threatscape report #advanced threat #aka apt39 #apt #belugasturgeon apt #blacksturgeon apt #chafer #microsoft #microsoft exchange #microsoft outlook #outlook on the web #owa #russia #sourface #tactics #turla apt #whitebear apt #windows internet information services

Disable APT Cache in Debian

In the Debian system, the packages are normally installed through the apt package manager, which installs the packages from the official Debian repository. The packages installed through apt are moved to the cache directory and are managed inside the location ‘/var/cache/apt/archives’. The reason to put these files in the cached directory is to ensure that the next time you install a dependent package of an existing package, it won’t install the same package again; instead, it will pick up the package from this location. As time passes, the package loses its worthiness and the time will come when it won’t require any more on the system. Thus, it is a good practice to disable the apt cache on the Debian system, as this will help free up some space.

Follow this article’s detailed guidelines to disable apt cache in Debian.

How to Disable APT Cache in Debian

An easy step-by-step instruction to disable apt cache in Debian is given below:

Step 1: First, you must create a 00clean-cache-dir file on the Debian system through nano editor:

sudo nano /etc/apt/apt.conf.d/00clean-cache-dir

Step 2: Within the file, you must add the following line:

DPkg::Post-Invoke {"/bin/rm -f /var/cache/apt/archives/*.deb || true";};

Step 3: Then save the clean cache file using “CTRL+X”, add “Y” and enter to exit.

Step 4: Then you have to create another file with “00disbale-cache-files” name:

sudo nano 00disable-cache-files

Step 5: Within this file, add the following lines:

Dir::Cache::srcpkgcache "";

Dir::Cache::pkgcache "";

Step 6: Save this file using Step 3.

This will disable the apt cache on the Debian system.

Step 7: Now the apt cache is disabled now, it’s better to empty the ‘/var/cache/apt/archives’ directory on Debian using the following command:

sudo rm -rf /var/cache/apt/archives

Step 8 (Optional): Alternatively, it’s a good practice if you run the following command to delete the cache:

sudo apt clean --dry-run

Step 9 (Optional): Further you can also remove the cache files and directories through the following command:

sudo apt clean

Step 10 (Optional): Let’s clean the system by removing the cache file and directories using the following command.

sudo apt autoclean

Conclusion

The apt cache on Debian can be disabled easily by creating a clean cache file inside the /etc/apt/apt.conf.d/ location. Then create another file with disable cache in the home location. Save both these files to disable the apt cache on Debian. It’s better to remove cache files and directories through “rm -rf” command or some apt commands that are optional but good practice if you run them on the terminal.

Original article source at: https://linuxhint.com/

#debian #cache 

A Template Language That Completely Separates Structure and Logic/Ruby

Curly

Curly is a template language that completely separates structure and logic. Instead of interspersing your HTML with snippets of Ruby, all logic is moved to a presenter class.

Installing

Installing Curly is as simple as running gem install curly-templates. If you're using Bundler to manage your dependencies, add this to your Gemfile

gem 'curly-templates'

Curly can also install an application layout file, replacing the .erb file commonly created by Rails. If you wish to use this, run the curly:install generator.

$ rails generate curly:install

How to use Curly

In order to use Curly for a view or partial, use the suffix .curly instead of .erb, e.g. app/views/posts/_comment.html.curly. Curly will look for a corresponding presenter class named Posts::CommentPresenter. By convention, these are placed in app/presenters/, so in this case the presenter would reside in app/presenters/posts/comment_presenter.rb. Note that presenters for partials are not prepended with an underscore.

Add some HTML to the partial template along with some Curly components:

<!-- app/views/posts/_comment.html.curly -->
<div class="comment">
  <p>
    {{author_link}} posted {{time_ago}} ago.
  </p>

  {{body}}

  {{#author?}}
    <p>{{deletion_link}}</p>
  {{/author?}}
</div>

The presenter will be responsible for providing the data for the components. Add the necessary Ruby code to the presenter:

# app/presenters/posts/comment_presenter.rb
class Posts::CommentPresenter < Curly::Presenter
  presents :comment

  def body
    SafeMarkdown.render(@comment.body)
  end

  def author_link
    link_to @comment.author.name, @comment.author, rel: "author"
  end

  def deletion_link
    link_to "Delete", @comment, method: :delete
  end

  def time_ago
    time_ago_in_words(@comment.created_at)
  end

  def author?
    @comment.author == current_user
  end
end

The partial can now be rendered like any other, e.g. by calling

render 'comment', comment: comment
render comment
render collection: post.comments

Curly components are surrounded by curly brackets, e.g. {{hello}}. They always map to a public method on the presenter class, in this case #hello. Methods ending in a question mark can be used for conditional blocks, e.g. {{#admin?}} ... {{/admin?}}.

Identifiers

Curly components can specify an identifier using the so-called dot notation: {{x.y.z}}. This can be very useful if the data you're accessing is hierarchical in nature. One common example is I18n:

<h1>{{i18n.homepage.header}}</h1>

# In the presenter, the identifier is passed as an argument to the method. The
# argument will always be a String.
def i18n(key)
  translate(key)
end

The identifier is separated from the component name with a dot. If the presenter method has a default value for the argument, the identifier is optional – otherwise it's mandatory.

Attributes

In addition to an identifier, Curly components can be annotated with attributes. These are key-value pairs that affect how a component is rendered.

The syntax is reminiscent of HTML:

<div>{{sidebar rows=3 width=200px title="I'm the sidebar!"}}</div>

The presenter method that implements the component must have a matching keyword argument:

def sidebar(rows: "1", width: "100px", title:); end

All argument values will be strings. A compilation error will be raised if

• an attribute is used in a component without a matching keyword argument being present in the method definition; or
• a required keyword argument in the method definition is not set as an attribute in the component.

You can define default values using Ruby's own syntax. Additionally, if the presenter method accepts arbitrary keyword arguments using the **doublesplat syntax then all attributes will be valid for the component, e.g.

def greetings(**names)
  names.map {|name, greeting| "#{name}: #{greeting}!" }.join("\n")
end

{{greetings alice=hello bob=hi}}
<!-- The above would be rendered as: -->
alice: hello!
bob: hi!

Note that since keyword arguments in Ruby are represented as Symbol objects, which are not garbage collected in Ruby versions less than 2.2, accepting arbitrary attributes represents a security vulnerability if your application allows untrusted Curly templates to be rendered. Only use this feature with trusted templates if you're not on Ruby 2.2 yet.

Conditional blocks

If there is some content you only want rendered under specific circumstances, you can use conditional blocks. The {{#admin?}}...{{/admin?}} syntax will only render the content of the block if the admin? method on the presenter returns true, while the {{^admin?}}...{{/admin?}} syntax will only render the content if it returns false.

Both forms can have an identifier: {{#locale.en?}}...{{/locale.en?}} will only render the block if the locale? method on the presenter returns true given the argument "en". Here's how to implement that method in the presenter:

class SomePresenter < Curly::Presenter
  # Allows rendering content only if the locale matches a specified identifier.
  def locale?(identifier)
    current_locale == identifier
  end
end

Furthermore, attributes can be set on the block. These only need to be specified when opening the block, not when closing it:

{{#square? width=3 height=3}}
  <p>It's square!</p>
{{/square?}}

Attributes work the same way as they do for normal components.

Collection blocks

Sometimes you want to render one or more items within the current template, and splitting out a separate template and rendering that in the presenter is too much overhead. You can instead define the template that should be used to render the items inline in the current template using the collection block syntax.

Collection blocks are opened using an asterisk:

{{*comments}}
  <li>{{body}} ({{author_name}})</li>
{{/comments}}

The presenter will need to expose the method #comments, which should return a collection of objects:

class Posts::ShowPresenter < Curly::Presenter
  presents :post

  def comments
    @post.comments
  end
end

The template within the collection block will be used to render each item, and it will be backed by a presenter named after the component – in this case, comments. The name will be singularized and Curly will try to find the presenter class in the following order:

• Posts::ShowPresenter::CommentPresenter
• Posts::CommentPresenter
• CommentPresenter

This allows you some flexibility with regards to how you want to organize these nested templates and presenters.

Note that the nested template will only have access to the methods on the nested presenter, but all variables passed to the "parent" presenter will be forwarded to the nested presenter. In addition, the current item in the collection will be passed, as well as that item's index in the collection:

class Posts::CommentPresenter < Curly::Presenter
  presents :post, :comment, :comment_counter

  def number
    # `comment_counter` is automatically set to the item's index in the collection,
    # starting with 1.
    @comment_counter
  end

  def body
    @comment.body
  end

  def author_name
    @comment.author.name
  end
end

Collection blocks are an alternative to splitting out a separate template and rendering that from the presenter – which solution is best depends on your use case.

Context blocks

While collection blocks allow you to define the template that should be used to render items in a collection right within the parent template, context blocks allow you to define the template for an arbitrary context. This is very powerful, and can be used to define widget-style components and helpers, and provide an easy way to work with structured data. Let's say you have a comment form on your page, and you'd rather keep the template inline. A simple template could look like:

<!-- post.html.curly -->
<h1>{{title}}</h1>
{{body}}

{{@comment_form}}
  <b>Name: </b> {{name_field}}<br>
  <b>E-mail: </b> {{email_field}}<br>
  {{comment_field}}

  {{submit_button}}
{{/comment_form}}

Note that an @ character is used to denote a context block. Like with collection blocks, a separate presenter class is used within the block, and a simple convention is used to find it. The name of the context component (in this case, comment_form) will be camel cased, and the current presenter's namespace will be searched:

class PostPresenter < Curly::Presenter
  presents :post
  def title; @post.title; end
  def body; markdown(@post.body); end

  # A context block method *must* take a block argument. The return value
  # of the method will be used when rendering. Calling the block argument will
  # render the nested template. If you pass a value when calling the block
  # argument it will be passed to the presenter.
  def comment_form(&block)
    form_for(Comment.new, &block)
  end

  # The presenter name is automatically deduced.
  class CommentFormPresenter < Curly::Presenter
    # The value passed to the block argument will be passed in a parameter named
    # after the component.
    presents :comment_form

    # Any parameters passed to the parent presenter will be forwarded to this
    # presenter as well.
    presents :post

    def name_field
      @comment_form.text_field :name
    end

    # ...
  end
end

Context blocks were designed to work well with Rails' helper methods such as form_for and content_tag, but you can also work directly with the block. For instance, if you want to directly control the value that is passed to the nested presenter, you can call the call method on the block yourself:

def author(&block)
  content_tag :div, class: "author" do
    # The return value of `call` will be the result of rendering the nested template
    # with the argument. You can post-process the string if you want.
    block.call(@post.author)
  end
end

Context shorthand syntax

If you find yourself opening a context block just in order to use a single component, e.g. {{@author}}{{name}}{{/author}}, you can use the shorthand syntax instead: {{author:name}}. This works for all component types, e.g.

{{#author:admin?}}
  <p>The author is an admin!</p>
{{/author:admin?}}

The syntax works for nested contexts as well, e.g. {{comment:author:name}}. Any identifier and attributes are passed to the target component, which in this example would be {{name}}.

Setting up state

Although most code in Curly presenters should be free of side effects, sometimes side effects are required. One common example is defining content for a content_for block.

If a Curly presenter class defines a setup! method, it will be called before the view is rendered:

class PostPresenter < Curly::Presenter
  presents :post

  def setup!
    content_for :title, post.title

    content_for :sidebar do
      render 'post_sidebar', post: post
    end
  end
end

Escaping Curly syntax

In order to have {{ appear verbatim in the rendered HTML, use the triple Curly escape syntax:

This is {{{escaped}}.

You don't need to escape the closing }}.

Comments

If you want to add comments to your Curly templates that are not visible in the rendered HTML, use the following syntax:

{{! This is some interesting stuff }}

Presenters

Presenters are classes that inherit from Curly::Presenter – they're usually placed in app/presenters/, but you can put them anywhere you'd like. The name of the presenter classes match the virtual path of the view they're part of, so if your controller is rendering posts/show, the Posts::ShowPresenter class will be used. Note that Curly is only used to render a view if a template can be found – in this case, at app/views/posts/show.html.curly.

Presenters can declare a list of accepted variables using the presents method:

class Posts::ShowPresenter < Curly::Presenter
  presents :post
end

A variable can have a default value:

class Posts::ShowPresenter < Curly::Presenter
  presents :post
  presents :comment, default: nil
end

Any public method defined on the presenter is made available to the template as a component:

class Posts::ShowPresenter < Curly::Presenter
  presents :post

  def title
    @post.title
  end

  def author_link
    # You can call any Rails helper from within a presenter instance:
    link_to author.name, profile_path(author), rel: "author"
  end

  private

  # Private methods are not available to the template, so they're safe to
  # use.
  def author
    @post.author
  end
end

Presenter methods can even take an argument. Say your Curly template has the content {{t.welcome_message}}, where welcome_message is an I18n key. The following presenter method would make the lookup work:

def t(key)
  translate(key)
end

That way, simple ``functions'' can be added to the Curly language. Make sure these do not have any side effects, though, as an important part of Curly is the idempotence of the templates.

Layouts and content blocks

Both layouts and content blocks (see content_for) use yield to signal that content can be inserted. Curly works just like ERB, so calling yield with no arguments will make the view usable as a layout, while passing a Symbol will make it try to read a content block with the given name:

# Given you have the following Curly template in
# app/views/layouts/application.html.curly
#
#   <html>
#     <head>
#       <title>{{title}}</title>
#     </head>
#     <body>
#       <div id="sidebar">{{sidebar}}</div>
#       {{body}}
#     </body>
#   </html>
#
class ApplicationLayout < Curly::Presenter
  def title
    "You can use methods just like in any other presenter!"
  end

  def sidebar
    # A view can call `content_for(:sidebar) { "some HTML here" }`
    yield :sidebar
  end

  def body
    # The view will be rendered and inserted here:
    yield
  end
end

Rails helper methods

In order to make a Rails helper method available as a component in your template, use the exposes_helper method:

class Layouts::ApplicationPresenter < Curly::Presenter
  # The components {{sign_in_path}} and {{root_path}} are made available.
  exposes_helper :sign_in_path, :root_path
end

Testing

Presenters can be tested directly, but sometimes it makes sense to integrate with Rails on some levels. Currently, only RSpec is directly supported, but you can easily instantiate a presenter:

SomePresenter.new(context, assigns)

context is a view context, i.e. an object that responds to render, has all the helper methods you expect, etc. You can pass in a test double and see what you need to stub out. assigns is the hash containing the controller and local assigns. You need to pass in a key for each argument the presenter expects.

Testing with RSpec

In order to test presenters with RSpec, make sure you have rspec-rails in your Gemfile. Given the following presenter:

# app/presenters/posts/show_presenter.rb
class Posts::ShowPresenter < Curly::Presenter
  presents :post

  def body
    Markdown.render(@post.body)
  end
end

You can test the presenter methods like this:

# You can put this in your `spec_helper.rb`.
require 'curly/rspec'

# spec/presenters/posts/show_presenter_spec.rb
describe Posts::ShowPresenter, type: :presenter do
  describe "#body" do
    it "renders the post's body as Markdown" do
      assign(:post, double(:post, body: "**hello!**"))
      expect(presenter.body).to eq "<strong>hello!</strong>"
    end
  end
end

Note that your spec must be tagged with type: :presenter.

Examples

Here is a simple Curly template – it will be looked up by Rails automatically.

<!-- app/views/posts/show.html.curly -->
<h1>{{title}}<h1>
<p class="author">{{author}}</p>
<p>{{description}}</p>

{{comment_form}}

<div class="comments">
  {{comments}}
</div>

When rendering the template, a presenter is automatically instantiated with the variables assigned in the controller or the render call. The presenter declares the variables it expects with presents, which takes a list of variables names.

# app/presenters/posts/show_presenter.rb
class Posts::ShowPresenter < Curly::Presenter
  presents :post

  def title
    @post.title
  end

  def author
    link_to(@post.author.name, @post.author, rel: "author")
  end

  def description
    Markdown.new(@post.description).to_html.html_safe
  end

  def comments
    render 'comment', collection: @post.comments
  end

  def comment_form
    if @post.comments_allowed?
      render 'comment_form', post: @post
    else
      content_tag(:p, "Comments are disabled for this post")
    end
  end
end

Caching

Caching is handled at two levels in Curly – statically and dynamically. Static caching concerns changes to your code and templates introduced by deploys. If you do not wish to clear your entire cache every time you deploy, you need a way to indicate that some view, helper, or other piece of logic has changed.

Dynamic caching concerns changes that happen on the fly, usually made by your users in the running system. You wish to cache a view or a partial and have it expire whenever some data is updated – usually whenever a specific record is changed.

Dynamic Caching

Because of the way logic is contained in presenters, caching entire views or partials by the data they present becomes exceedingly straightforward. Simply define a #cache_key method that returns a non-nil object, and the return value will be used to cache the template.

Whereas in ERB you would include the cache call in the template itself:

<% cache([@post, signed_in?]) do %>
  ...
<% end %>

In Curly you would instead declare it in the presenter:

class Posts::ShowPresenter < Curly::Presenter
  presents :post

  def cache_key
    [@post, signed_in?]
  end
end

Likewise, you can add a #cache_duration method if you wish to automatically expire the fragment cache:

class Posts::ShowPresenter < Curly::Presenter
  ...

  def cache_duration
    30.minutes
  end
end

In order to set any cache option, define a #cache_options method that returns a Hash of options:

class Posts::ShowPresenter < Curly::Presenter
  ...

  def cache_options
    { compress: true, namespace: "my-app" }
  end
end

Static Caching

Static caching will only be enabled for presenters that define a non-nil #cache_key method (see Dynamic Caching.)

In order to make a deploy expire the cache for a specific view, set the version of the view to something new, usually by incrementing by one:

class Posts::ShowPresenter < Curly::Presenter
  version 3

  def cache_key
    # Some objects
  end
end

This will change the cache keys for all instances of that view, effectively expiring the old cache entries.

This works well for views, or for partials that are rendered in views that themselves are not cached. If the partial is nested within a view that is cached, however, the outer cache will not be expired. The solution is to register that the inner partial is a dependency of the outer one such that Curly can automatically deduce that the outer partial cache should be expired:

class Posts::ShowPresenter < Curly::Presenter
  version 3
  depends_on 'posts/comment'

  def cache_key
    # Some objects
  end
end

class Posts::CommentPresenter < Curly::Presenter
  version 4

  def cache_key
    # Some objects
  end
end

Now, if the version of Posts::CommentPresenter is bumped, the cache keys for both presenters would change. You can register any number of view paths with depends_on.

Curly integrates well with the caching mechanism in Rails 4 (or Cache Digests in Rails 3), so the dependencies defined with depends_on will be tracked by Rails. This will allow you to deploy changes to your templates and have the relevant caches automatically expire.

Thanks

Thanks to Zendesk for sponsoring the work on Curly.

Contributors

• Daniel Schierbeck (@dasch)
• Benjamin Quorning (@bquorning)
• Jeremy Rodi (@medcat)
• Alisson Cavalcante Agiani (@thelinuxlich)
• Łukasz Niemier (@hauleth)
• Cristian Planas (@Gawyn)
• Steven Davidovitz (@steved)

Build Status

---

Author: zendesk
Source code: https://github.com/zendesk/curly

#ruby   #ruby-on-rails 

How to List Installed Repositories In Ubuntu & Debian

A repository is the collection of packages for a Linux operating system. You can create a central repository containing the actual packages. Then configure your other systems to connect with the main repository. From where, you can install, update packages.

The Ubuntu and other Debian based systems uses APT (Advanced Packages Tool) as package manager. Apt keeps all the configuration files under /etc/apt directory.

This tutorial will help you to list all installed repositories under a Ubuntu or Debian based system via command line.

List Installed Repositories In Ubuntu

The remote repository references are configured in /etc/apt/sources.list file and all files under /etc/apt/sources.list.d/ directory.

Use the following command to list all the configured repositories on apt based system:

sudo grep -rhE ^deb /etc/apt/sources.list* 

You will see the output like below:

deb http://mirrors.digitalocean.com/ubuntu/ xenial main restricted
deb-src http://mirrors.digitalocean.com/ubuntu/ xenial main restricted
deb http://mirrors.digitalocean.com/ubuntu/ xenial-updates main restricted
deb-src http://mirrors.digitalocean.com/ubuntu/ xenial-updates main restricted
deb http://mirrors.digitalocean.com/ubuntu/ xenial universe
deb-src http://mirrors.digitalocean.com/ubuntu/ xenial universe
.
.
.
deb http://security.ubuntu.com/ubuntu xenial-security universe
deb-src http://security.ubuntu.com/ubuntu xenial-security universe
deb http://security.ubuntu.com/ubuntu xenial-security multiverse
deb-src http://security.ubuntu.com/ubuntu xenial-security multiverse

Alternatively, you can use apt-cache command to list all repositories. This command will provide also provide more details about the repository.

#debian #apt #debian #repository #ubuntu