Method: Open3.popen2

Defined in:

lib/open3.rb

.popen2(*cmd, **opts, &block) ⇒ Object

Open3.popen2 is similar to Open3.popen3 except that it doesn’t create a pipe for the standard error stream.

Block form:

Open3.popen2([env,] cmd... [, opts]) {|stdin, stdout, wait_thr|
  pid = wait_thr.pid # pid of the started process.
  ...
  exit_status = wait_thr.value # Process::Status object returned.
}

Non-block form:

stdin, stdout, wait_thr = Open3.popen2([env,] cmd... [, opts])
...
stdin.close  # stdin and stdout should be closed explicitly in this form.
stdout.close

See Process.spawn for the optional hash arguments env and opts.

Example:

Open3.popen2("wc -c") {|i,o,t|
  i.print "answer to life the universe and everything"
  i.close
  p o.gets #=> "42\n"
}

Open3.popen2("bc -q") {|i,o,t|
  i.puts "obase=13"
  i.puts "6 * 9"
  p o.gets #=> "42\n"
}

Open3.popen2("dc") {|i,o,t|
  i.print "42P"
  i.close
  p o.read #=> "*"
}

# File 'lib/open3.rb', line 137

def popen2(*cmd, **opts, &block)
  in_r, in_w = IO.pipe
  opts[:in] = in_r
  in_w.sync = true

  out_r, out_w = IO.pipe
  opts[:out] = out_w

  popen_run(cmd, opts, [in_r, out_w], [in_w, out_r], &block)
end