Module: Process

Defined in:
lib/procreate.rb

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.create(cmdline, params = {}) ⇒ Object

Process.create is a thin, cross-platform wrapper around Open4.background.

The given cmdline is run in a background process and a thread object is returned as a handle. The thread is extended with the Process module, to facilitate testing for a process object and provide an extension point. Methods are provided to retrieve the #pid or #exitstatus.

It takes arguments for :stdin, :stdout, and :stderr redirection, and also a :shell parameter which determines whether or not the command line should be run by a shell.

The default if no streams are provided is that output is thrown away. You need to explicitly pass eg :stdout => STDOUT if you want to keep STDOUT from process.

Currently the shell is avoided where possible to ensure the pid is that of the actual process, so it can be signaled (ie killed) reliably. Otherwise, the pid is that of the shell, and any signalling to that pid works as per the shell’s documentation.



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# File 'lib/procreate.rb', line 40

def Process.create cmdline, params={}
  params = params.dup
  shell = params.delete(:shell) # default is false, so nil is okay
  if RUBY_PLATFORM !~ /mswin|mingw/
    if Array === cmdline
      raise ArgumentError, 'unable to use shell with array command' if shell
    elsif shell
      # nothing to do. exec will use /bin/sh anyway
    else
      # avoid use of shell, so that #pid on return value is actual process pid
      # not shell pid
      require 'shellwords'
      cmdline = Shellwords.shellwords cmdline.to_s
      cmdline = [cmdline, cmdline].transpose if cmdline.length == 1
    end
    # just due to different behaviour for Open4 unix
    params.update :status => true
  else
    if Array === cmdline
      # the windows version doesn't support array form of cmdline (though could
      # perhaps fake using some shell quoting thing).
      raise ArgumentError, 'array arguments not supported on windows'
    elsif shell
      # it won't use the shell by default with CreateProcess.
      # so force it to do so here:
      # FIXME, this should really be ENV['COMSPEC'] or whatever.
      cmdline = "cmd /c #{cmdline}"
    else
      # nothing to do
    end
  end
  Open4.background(cmdline, params).extend(Process)
end

Instance Method Details

#exitstatus ⇒ Object

Return the process exit status. Will block until the process finishes executing.

Raises:

  • (NotImplementedError) 


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# File 'lib/procreate.rb', line 15

def exitstatus
  raise NotImplementedError
end

#pid ⇒ Object

Return the pid of the process.

Raises:

  • (NotImplementedError) 


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# File 'lib/procreate.rb', line 9

def pid
  raise NotImplementedError
end