URLS: |

http://raa.ruby-lang.org/project/session/
http://www.codeforpeople.com/lib/ruby/session/

NAME: |

Session
::Sh
::Bash
::Shell
::IDL

SYNOPSIS: |

Session::* offers a set of classes built upon Open3::popen3 for driving
external progams via pipes.  It offers a significant abstraction over
Open3::popen in that the stdout/stderr of each command sent can be deliniated:

open3:

    i,o,e = Open3::popen3 '/bin/sh'

    i.puts 'ls'
    i.puts 'echo 42'

now, how to determine the boundry between the output from 'ls' and 'echo'?
the only (simple) way is start a process for each command

    i,o,e = Open3::popen3 '/bin/sh'
    i.puts 'ls'
    i.close
    stdout, stderr = o.read, e.read

    i,o,e = Open3::popen3 '/bin/sh'
    i.puts 'echo 42'
    i.close
    stdout, stderr = o.read, e.read

session:

  sh = Session::new

  stdout, stderr = sh.execute 'ls'
  stdout, stderr = sh.execute 'echo 42'

Both stderr and stdout can be redirected, and the exit_status of each command
is made available:

  bash = Session::Bash.new
  stdout, stderr = StringIO::new, StringIO::new

  bash.execute 'ls', :stdout => stdout, :stderr => stderr
  # bash.execute 'ls', 1 => stdout, 2 => stderr           # same thing
  # bash.execute 'ls', :o => stdout, :e => stderr         # same thing

  exit_status = bash.exit_status

A block form can be used to specify a callback to be invoked whenever output
has become availible:

bash = Session::Bash.new

bash.execute( 'long_running_command.exe' ) do |out, err|
  logger << out if out
  elogger << err if err
end

Sessions are Thread safe (in the sense that they do not block on io
operations) allowing commands spawned from guis to update widgets with output
while running in the background.

button.configure 'action' => lambda do
  sh = Session::new
  sh.execute(cmd) do |o,e|
    out_widget.update o if o
    err_widget.update e if e
  end
end

SAMPLES: |

see samples/*

HISTORY: | 3.1.0: - patches from @headius

3.0.0
- move to github

2.4.0:
- added ability to specify stdin for Session::Bash and Session::Sh

    sh = Session::new

    sh.execute 'cat', :stdin => io
    sh.execute 'cat', :stdin => string
    sh.execute 'cat', :stdin => stringio

2.3.0:
- fixed warning of @debug being un-initialized

2.2.0:
- added a private munged version of Open3::open3.  the builtin one causes
  the child process to become a child of init, this was very inconvenient
  because it was sometimes hard to crawl proces trees - the parent was lost.
  now the seesion is a child process that has been detached using
  Process::detach.  this results in less suprising behaviour; for instance
  sending signal TERM to a process results in any sessions it had open dying
  as well.  you can use Session::use_open3=true or
  ENV['SESSION_USE_OPEN3']='1' for the old behaviour if you need it.
- added Session::Bash::Login class.  this class opens a session which has
  all the normal settings of a bash loging shell (.bashrc is sourced).  this
  if often convenient as paths, aliases, etc. are set as normal.
- moved the Spawn module inside the Session module.  now the Session module
  is the namespace for everything so using session pollutes namespace less.

2.1.9:
- fixed bug where setting track history after creation caused later failure in
  execute (@history =[] only in ctor).  thanks leon breedt
  <bitserf@gmail.com>!
- updates to README
- included session-x.x.x.rpa file - thanks batsman <batsman.geo@yahoo.com>
- to_str/to_s/to_yaml for History/Command is now valid yaml (updated samples
  to reflect this)
- inspect for History/Command is now ruby's default 

2.1.8:
- greatly simplified read loop using two reader threads, one for stderr and
  one for stdout alongside a mutex to protect data.  this streamlined the code
  alot vs. the old select method including allowing removal of the linbuffer
  class.  the interface remains exactly as before however.

2.1.7:
- improved thread safe non-blocking read method
- gemspec 

2.1.6:
- wrapped send_command in a Thread (send async) so output processing can
  commend immeadiately.  this was o.k. before, but had strange behaviour when
  using popen3 from threads.  thanks to tanaka akira for this suggestion.
- iff ENV['SESSION_USE_SPAWN'] is set Session uses Spawn::spawn instead of
  Open3::popen3.  also noted that spawn seems to be a bit faster.
- added tests for threads.
- run 'sh SESSION_USE_SPAWN=1 ruby test/session.rb' to test using spawn
- added test for idl so it's test is not run if system doesn't have it, all
  that should be required for 'ruby test/session.rb' is should be sh'
- removed sample/tcsh and note about Tcsh and Csh in README - stderr
  redirection/separation is flaky in those shells

2.1.5:
- added Session.use_spawn=, AbstractSession.use_spawn=, and an :use_session=>
  option to AbstractSession#initialize.  if any of them are set the code uses
  Spawn::spawn to create external processes instead of Open3::popen3.
  Spawn::spawn uses named pipes (fifos) for IPC instead of forking and pipes.
  the fork used in popen3 can cause strange behaviour with multi-threaded apps
  (like a tk app).  see source for details

2.1.4:
- added Thread.exclusive{} wrapper when io is read to works in multi
  threaded apps

AUTHOR: |

ara.t.howard@noaa.gov