Vagrant - how to have host platform specific provisioning steps

Find out current OS inside Vagrantfile.

Add this into your Vagrantfile:

module OS
    def OS.windows?
        (/cygwin|mswin|mingw|bccwin|wince|emx/ =~ RUBY_PLATFORM) != nil
    end

    def OS.mac?
        (/darwin/ =~ RUBY_PLATFORM) != nil
    end

    def OS.unix?
        !OS.windows?
    end

    def OS.linux?
        OS.unix? and not OS.mac?
    end
end

Then you can use it as you like.

if OS.windows? [then]
    code...
end

Edit: was missing the ? on if condition.

Example used to test:

is_windows_host = "#{OS.windows?}"
puts "is_windows_host: #{OS.windows?}"
if OS.windows?
    puts "Vagrant launched from windows."
elsif OS.mac?
    puts "Vagrant launched from mac."
elsif OS.unix?
    puts "Vagrant launched from unix."
elsif OS.linux?
    puts "Vagrant launched from linux."
else
    puts "Vagrant launched from unknown platform."
end

Execute:

# Ran provision to call Vagrantfile.
$ vagrant provision
is_windows_host: false
Vagrant launched from mac.

Note that Vagrant itself, in the Vagrant::Util::Platform class already implements a more advanced version of the platform checking logic in the answer by BernardoSilva.

So in a Vagrantfile, you can simply use the following:

if Vagrant::Util::Platform.windows? then
    myHomeDir = ENV["USERPROFILE"]
else
    myHomeDir = "~"
end

Here is a version using the Vagrant utils that checks for mac and windows:

    if Vagrant::Util::Platform.windows?
        # is windows
    elsif Vagrant::Util::Platform.darwin?
        # is mac
    else
        # is linux or some other OS
    end