Method: LibGems::Installer#shebang

Defined in:
lib/libgems/installer.rb

#shebang(bin_file_name) ⇒ Object

Generates a #! line for bin_file_name‘s wrapper copying arguments if necessary.

If the :custom_shebang config is set, then it is used as a template for how to create the shebang used for to run a gem’s executables.

The template supports 4 expansions:

$env    the path to the unix env utility
$ruby   the path to the currently running ruby interpreter
$exec   the path to the gem's executable
$name   the name of the gem the executable is for



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# File 'lib/libgems/installer.rb', line 353

def shebang(bin_file_name)
  ruby_name = LibGems::ConfigMap[:ruby_install_name] if @env_shebang
  path = File.join @gem_dir, @spec.bindir, bin_file_name
  first_line = File.open(path, "rb") {|file| file.gets}

  if /\A#!/ =~ first_line then
    # Preserve extra words on shebang line, like "-w".  Thanks RPA.
    shebang = first_line.sub(/\A\#!.*?ruby\S*(?=(\s+\S+))/, "#!#{LibGems.ruby}")
    opts = $1
    shebang.strip! # Avoid nasty ^M issues.
  end

  if which = LibGems.configuration[:custom_shebang]
    which = which.gsub(/\$(\w+)/) do
      case $1
      when "env"
        @env_path ||= ENV_PATHS.find do |env_path|
                        File.executable? env_path
                      end
      when "ruby"
        "#{LibGems.ruby}#{opts}"
      when "exec"
        bin_file_name
      when "name"
        spec.name
      end
    end

    return "#!#{which}"
  end

  if not ruby_name then
    "#!#{LibGems.ruby}#{opts}"
  elsif opts then
    "#!/bin/sh\n'exec' #{ruby_name.dump} '-x' \"$0\" \"$@\"\n#{shebang}"
  else
    # Create a plain shebang line.
    @env_path ||= ENV_PATHS.find {|env_path| File.executable? env_path }
    "#!#{@env_path} #{ruby_name}"
  end
end