I am trying to create a named pipe inside Ruby. Besides using the system command (system("mkfifo #{pipe_name}")), is there a native Ruby function allowing me to do this?
Current versions of Ruby (starting with 2.3.0) now have a native File::mkfifo:
File.mkfifo('pipe_name')
Old answer for older versions of Ruby:
I don't believe there's anything fully native, but there's the mkfifo gem.
Install like this:
gem install mkfifo
Then use like this:
require "mkfifo"
File.mkfifo('pipe_name')
Related
I can gem open #{gem_name} (command line) to see the source of installed gems. But how do I view the source of e.g. openssl which is in ruby core?
(Without going to the github repo... is there a command to view it locally?)
There isn't one. The reason most probably is that gems shipped with Ruby aren't treated in a different way than the core code. That said, the libraries are located under ext/.
If you want to find specific code (assuming it's Ruby and not C), you can always do
foo.method(:bar).source_location
Foo.instance_method(:bar).source_location
I have an app that requires Ruby 2.1 and use Puppet to provision a handful of servers.
The problem is, when I install on the 2.1 version of Ruby, Puppet starts using that, and it is not supported.
I would like to somehow point Puppet to a 2.0 version of Ruby installed in /opt.
Any suggestions?
Perhaps you could add a shebang line in the .rb file that points to the other version of ruby?
Alternatively you could try to specifically add the bin/ruby location in /opt to the $PATH variable.
Typically, you shouldn't let the system determine the path, but instead provide the full path to the Ruby interpreter you want to execute your script:
/usr/bin/ruby /some/path/to/foo.rb
Or:
/usr/local/bin/ruby1.9.2 /path/to/bar.rb
I have build a gem and want it to print its version.
I cant use Gem::Specification.find_by_name('mygem').version
because there are several versions of it installed.
Lets just say my program has just a single src file /bin/myruby containing this:
#!/usr/bin/env ruby
mygem_version = ???
puts "This is my gems version: #{mygem_version}"
A common convention is to create a lib/<your_gem_name>/version.rb that defines a YourGemName::VERSION constant. Then, you can refer to that constant in your gemspec, which is Ruby code that gets evaluated when the gem is built.
Read http://timelessrepo.com/making-ruby-gems for a guide that uses this approach.
If you're using Bundler (think rails), try
Bundler.definition.specs
else, make sure your gem has a VERSION constant you can ask these things
This worked for me and always returned the correct version.
#!/usr/bin/env ruby
puts "This is my gems version: #{Gem.loaded_specs['mygem'].version}"
I want to get list of all installed packages on my machine using ruby gem or plugin. Functionality is similar to dpkg -l command on ubuntu. Is there any appropriate ruby gem or plugin available to get the same?
If you mean Ruby gems, then
gem list
You can execute a shell command inside the ruby interpreter. In your case, simply run
`dpkg -l`
The output will be a string containing the output of the command. Please note the `.
Keep in mind there are several ways to perform a shell command in Ruby.
There is a Debian package called ruby-debian (in older Debian releases it is called dpkg-ruby) which contains Ruby bindings to dkpg.
Note: it relies on a C extension, so it will not work on Ruby implementations that don't support them, such as IronRuby.
Been running into a problem ever since I started using rvm to manage my ruby installation. Whenever I want to require another class I've written, such as require 'filename', I get a require - no such file to load error when I try to run my script. If I switch back to my system ruby using rvm use system it works again, but I'm 1.8.2 as my system ruby and some features I want to use in my code are only available in 1.9.*, which I can access through rvm. How do I fix this problem?
I'm not sure this is a problem with RVM, but a problem with Ruby 1.9 not including '.' in the current path. For instance, if you are trying to require a library at './lib/file.rb', you can't do
require "lib/file"
You have to do this:
require "./lib/file"
Have you tried that syntax for your require?
I think you want to use require_relative
http://extensions.rubyforge.org/rdoc/classes/Kernel.html