open

Allocates a pty (pseudo-terminal).

In the non-block form, returns a two element array, [master_io, slave_file].

In the block form, yields two arguments master_io, slave_file and the value of the block is returned from open.

The IO and File are both closed after the block completes if they haven’t been already closed.

The arguments in both forms are:

Example

PTY.open {|m, s|
  p m      #=> #<IO:masterpty:/dev/pts/1>
  p s      #=> #<File:/dev/pts/1>
  p s.path #=> "/dev/pts/1"
}

# Change the buffering type in factor command,
# assuming that factor uses stdio for stdout buffering.
# If IO.pipe is used instead of PTY.open,
# this code deadlocks because factor's stdout is fully buffered.
require 'io/console' # for IO#raw!
m, s = PTY.open
s.raw! # disable newline conversion.
r, w = IO.pipe
pid = spawn("factor", :in=>r, :out=>s)
r.close
s.close
w.puts "42"
p m.gets #=> "42: 2 3 7\n"
w.puts "144"
p m.gets #=> "144: 2 2 2 2 3 3\n"
w.close
# The result of read operation when pty slave is closed is platform
# dependent.
ret = begin
        m.gets          # FreeBSD returns nil.
      rescue Errno::EIO # GNU/Linux raises EIO.
        nil
      end
p ret #=> nil