Ruby has the *nix `rm -rf` equivalent in the [FileUtils][1] module that you can use to delete both files and non-empty folders/directories:

    FileUtils.rm_rf(&#39;dir/to/remove&#39;)

To keep the directory itself and only remove its contents:

    FileUtils.rm_rf(Dir.glob(&#39;dir/to/remove/*&#39;))

    FileUtils.rm_rf(Dir[&#39;dir/to/remove/*&#39;])      # shorter version of above


  [1]: http://ruby-doc.org/stdlib/libdoc/fileutils/rdoc/FileUtils.html

You can run arbitrary commands using backticks like so:

    `rm -fr public/cache/*`

This may be more platform-dependent than what you want, but it opens up a lot of possibilities.

Great answers here already. You might also be interested to know that Rails 5 has a rake task to do this built-in:


    rake tmp:cache:clear # Clear cache files from tmp/


Is there an elegant to emulate the `StreamReader.ReadToEnd` method with `BinaryReader`? Perhaps to put all the bytes into a byte array?

I do this:

    read1.ReadBytes((int)read1.BaseStream.Length);

...but there must be a better way.

An elegant way to consume (all bytes of a) BinaryReader?

Is there a variant of `subprocess.call` that can run the command without printing to standard out, or a way to block out it&#39;s standard out messages? 

Is there a quiet version of subprocess.call?

I have a `public/cache` folder which has files and folders. How can I completely empty that folder using a rake task?

How to delete all contents of a folder with Ruby-Rails?

<p>I have a <code>public/cache</code> folder which has files and folders. How can I completely empty that folder using a rake task?</p>


Is there a Ruby class/method where I could pass &quot;a full path&quot;, `home/me/a_file.txt`, to identify whether it is a valid file path?



How to check for file existence

This seems to be basic but I&#39;m a Ruby/Rails beginner. I need to simply return HTTP 204 in a controller.
Would  
 

    respond_to do |format|
      format.html  
    end

return a 204?

How to return HTTP 204 in a Rails controller

How do I list all the methods that a particular object has access to?

I have a `@current_user` object, defined in the application controller:

    def current_user
      @current_user ||= User.find(session[:user_id]) if session[:user_id]
    end

And want to see what methods I have available to me in the view file. Specifically, I want to see what methods a `:has_many` association provides. (I know what `:has_many` *should* provide, but want to check that.)

How to list all methods for an object in Ruby?

How to check if a variable is a number or a string in Ruby?

How to check if a variable is a number or a string?

I am using Heroku for my application and it requires PostgreSQL but you can still use SQLite3 for development. Since Heroku strongly advised against having 2 different databases I decided to change to PostgreSQL for development. I installed the `gem pg` and also went to the official PostgreSQL site to get the Windows installer and also changed my `database.yml`. During installation it requires a password for PostgreSQL so I made one. 
I had to change the `pg_hba.conf` file from using `md5` to `trust` in order get past: `fe_sendauth: no password supplied` when trying to create the database.

    # TYPE  DATABASE        USER            ADDRESS                 METHOD
    
    # IPv4 local connections:
    host    all             all             127.0.0.1/32            trust # was md5
    # IPv6 local connections:
    host    all             all             ::1/128                 trust # was md5
    # Allow replication connections from localhost, by a user with the
    # replication privilege.
    #host    replication     postgres        127.0.0.1/32            trust
    #host    replication     postgres        ::1/128                 trust

After getting rid of that though, I now get this:

    $ rake db:create
    (in C:/app)
    FATAL:  role &quot;User&quot; does not exist 
    Couldn&#39;t create database for {&quot;adapter&quot;=&gt;&quot;postgresql&quot;, &quot;encoding&quot;=&gt;&quot;utf8&quot;, 
    &quot;database&quot;=&gt;&quot;app_test&quot;, &quot;pool&quot;=&gt;5, &quot;username&quot;=&gt;nil, &quot;password&quot;=&gt;nil} 

I do still have my `development.sqlite3` and `text.sqlite3` present, could that be the issue? What must be done?

Here is my full gist: https://gist.github.com/1522188







Role does not exist and unable to create database when using PostgreSQL

I&#39;ve seen a few questions (namely [this one][1]) here on SO about adding a default boolean value to an existing column. So I tried the `change_column` suggestion but I mustn&#39;t be doing it right.

I tried:

    $ change_column :profiles, :show_attribute, :boolean, :default =&gt; true

Which returns `-bash: change_column: command not found`

I then ran:

    $ rails g change_column :profiles, :show_attribute, :boolean, :default =&gt; true

...and

    $ rails change_column :profiles, :show_attribute, :boolean, :default =&gt; true

Then ran `rake db:migrate`, but the value for `:show_attribute` remained `nil`. In the question I referenced above it says in PostgreSQL you need to update it manually. Since I&#39;m using PostgreSQL I added the following in my `create_profiles` migration:

    t.boolean :show_attribute, :default =&gt; true

Can someone tell me what I&#39;m doing wrong here?

  [1]: https://stackoverflow.com/questions/7098602/add-a-default-value-to-a-column-through-a-migration

Adding :default =&gt; true to boolean in existing Rails column

I am using seed.rb to populate both my development and production database. I usually populate the first with dummy data and the latter with the real minimal data that my app needs to run (e.g. the first user and so on).

How can I specify in seed.rb for what environment each data is?

Given that I know &quot;group&quot; to be a Gemfile method, I&#39;d like to achieve the same behavior for seed.rb.

E.g. I&#39;d like to write something like this in my seed.rb:

    group :development do 
      # development specific seeding code
    end

    group :production do 
      # production specific seeding code
    end

    # non-specific seeding code (it always runs) 

This to be able to call both the development-specific and the non-specific code with

    $ rake db:seed

And to call both the production-specific and the non-specific code with:

    $ rake db:seed RAILS_ENV=production 


Thank you

How to use seed.rb to selectively populate development and/or production databases?

I have a model named `Song`. I also have a model named `Listen`. A `Listen` `belongs_to :song`, and a song `:has_many listens` (can be listen to many times).

In my model I want to define a method `self.top` which should return the top 5 songs listened to the most. How can I achieve that using the `has_many` relation?

I&#39;m using Rails 3.1.

Thanks!

Rails 3 ActiveRecord: Order by count on association

&gt; **Possible Duplicate:**  
&gt; [Best way to use html5 data attributes with rails content\_tag helper?](https://stackoverflow.com/questions/4258512/best-way-to-use-html5-data-attributes-with-rails-content-tag-helper)  

&lt;!-- End of automatically inserted text --&gt;

How can I use html5 `data-*` attrubute in my link_to helper (Rails)

The API says that I have to use this format `link_to(body, url, html_options = {})` but I have an error when I put it in html_options

Ex: 

    link_to &quot;whatever&quot;, @whatever_path, { class: &#39;my_class&#39;, data-tooltip: &#39;what I want&#39; }

Content Type	Original Author	Original Content on Stackoverflow
Question	Jacob	View Question on Stackoverflow
Solution 1 - Ruby	Marek Příhoda	View Answer on Stackoverflow
Solution 2 - Ruby	James Watkins	View Answer on Stackoverflow
Solution 3 - Ruby	Gabe Kopley	View Answer on Stackoverflow

How to delete all contents of a folder with Ruby-Rails?

Ruby Problem Overview

Ruby Solutions

Solution 1 - Ruby

Solution 2 - Ruby

Solution 3 - Ruby

Is there a quiet version of subprocess.call?

An elegant way to consume (all bytes of a) BinaryReader?

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