method

popen3

v1_9_1_378 - Show latest stable - 0 notes - Class: Open3

popen3(*cmd) public

Open stdin, stdout, and stderr streams and start external executable. In addition, a thread for waiting the started process is noticed. The thread has a thread variable :pid which is the pid of the started process.

Non-block form:

stdin, stdout, stderr, wait_thr = Open3.popen3(cmd)
pid = wait_thr[:pid]  # pid of the started process.
...
stdin.close  # stdin, stdout and stderr should be closed in this form.
stdout.close
stderr.close
exit_status = wait_thr.value  # Process::Status object returned.

Block form:

Open3.popen3(cmd) { |stdin, stdout, stderr, wait_thr| ... }

The parameter cmd is passed directly to Kernel#spawn.

wait_thr.value waits the termination of the process. The block form also waits the process when it returns.

Closing stdin, stdout and stderr does not wait the process.

Show source

# File lib/open3.rb, line 62
  def popen3(*cmd)
    pw = IO::pipe   # pipe[0] for read, pipe[1] for write
    pr = IO::pipe
    pe = IO::pipe

    pid = spawn(*cmd, STDIN=>pw[0], STDOUT=>pr[1], STDERR=>pe[1])
    wait_thr = Process.detach(pid)
    pw[0].close
    pr[1].close
    pe[1].close
    pi = [pw[1], pr[0], pe[0], wait_thr]
    pw[1].sync = true
    if defined? yield
      begin
        return yield(*pi)
      ensure
        [pw[1], pr[0], pe[0]].each{|p| p.close unless p.closed?}
        wait_thr.join
      end
    end
    pi
  end

popen3

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