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########## Shell Commands ##########	
Installation:
$ gem install capistrano

Add your application to Capistrano (capify):
$ capify .

# NOTE: Rake access to capistrano is deprecated in Capistrano 1.3.
#       Use the 'cap' command instead.

Execute the setup task:
$ cap deploy:setup

Deploy your application:
$ cap deploy

Similar to deploy, but it runs the migrate task on the new release before
updating the symlink:
$ cap deploy:migrations

Rollback a release from production:
$ rake rollback

Deploy a particular revision from Subversion
$ cap deploy -s revision=1234

Execute the disable_web task:
$ rake remote_exec ACTION=disable_web \
UNTIL="tomorrow morning" \
REASON="vital upgrade"

Using the invoke task:
$ rake remote_exec ACTION=invoke \
COMMAND="svn up /u/apps/flipper/current/app/views" \
ROLES=app


########## Standard Tasks ##########
cleans up the releases directory, leaving the five most recent releases:
$ cap cleanup 

used when deploying an application for the first time. Starts the
application’s
spinner (via the spinner task) and then does a normal deploy:
$ cap cold_deploy 

updates all the code on your server (via update_code and symlink
tasks), then restarts the FastCGI listeners on the application servers (via
the restart task):
$ cap deploy

prints the difference between what was last deployed, and what is
currently in your repository:
$ cap diff_from_last_deploy

puts up a static maintenance page that is displayed to visitors:
$ cap disable_web

removes the maintenance page:
$ cap enable_web

allows you to send commands directly:
$ cap invoke

changes to the directory of your current release (as indicated by the
current symlink), and runs rake RAILS_ENV=production migrate:
$ cap migrate

restarts all FastCGI listeners for your application by calling the reaper
command without arguments. Only executed on :app servers
$ cap restart

rolls your application back to the previously deployed version
determines the previous release , updates the current symlink to point
to that, and then deletes the latest release
$ cap rollback

Creates and chmods the directory tree properly:
$ cap setup

inspect the existing tasks and display them to standard out in
alphabetical order, along with their descriptions:
$ cap show_tasks

starts the spinner process for your application:
$ cap spinner

updates the current symlink to the latest deployed version of the code
$ cap symlink

Checks out your source code, deletes the log and public/system
directories in your new release, symlinks log to
#{shared_path}/log, symlinks public/system to #{shared_path}/system:
$ cap update_code


########## config/deploy.rb ##########
*Defining Tasks
task :hello_world do
  run "echo Hello, $HOSTNAME"
end

task :hello_world, :roles => [:db, :app] do
  puts "calling hello_world..."
  hello_world
end

*Transactions
task :cold_deploy do
  transaction do
    task_one_here
    task_two_here
  end
  task_three_not_in_transaction
end

*Capturing output with run
run "sudo ls -la" do |channel, stream, data|
  if data =~ /^Password:/
    logger.info "#{channel[:host]} asked for password"
    channel.send_data "mypass\n"
  end
end

buffer = render(:template => 
<<EXAMPLE_TEMPLATE)
  This template will be rendered replacing variables
  <%= like_this_variable =>
  with their values.
EXAMPLE_TEMPLATE

put buffer, "path/to/save/file.txt", :mode => 0755

* multi-stage
set :stages, %w(staging production testing) # [optional] defaults to
[development, test, staging?, production].
set :default_stage, "testing" # [optional] if omitted, cap aborts if you don't
specify in args
require 'capistrano/ext/multistage'

Stage-specific code in config/deploy/staging.rb and config/deploy/production.rb.
see: http://weblog.jamisbuck.org/2007/7/23/capistrano-multistage

*deploy.rb variables and their defaults

The name of your application. 
:application	(required)	

The location of your code’s scm repository
:repository	(required)	

The address of the server to use as a gateway. 
:gateway	nil		

The name of the user to use when logging into the remote host(s).
:user		current_user	

The password to use for logging into the remote host(s).
:password	password	

The root of the directory tree on the remote host(s) that the 
application should be deployed to
:deploy_to	“/u/apps/#{application}”

The directory under deploy_to that should contain each deployed revision.
:version_dir	releases	

The name to use (relative to deploy_to) for the symlink that points at 
the current release
:current_dir	current		

The name of the directory under deploy_to that will contain directories and
files to be shared between all releases.
:shared_dir	shared	

This specifies the revision you want to check out on the remote machines.
:revision	(latest)	

The source control module to use. 
Current supported are :subversion, :cvs, :darcs
:scm		subversion	

The location on the remote host of the source control executable.
:svn,:cvs,:darcs

The subversion operation to use when checking out code on the remote host. 
Can be set to “export”
:checkout	"co"		
				
Hash of additional options passed to the SSH connection routine.
This lets you set (among other things) a non-standard port to connect on:
(ssh_options[:port] = 2345)
:ssh_options	Hash.new	
				
Whether or not tasks that can use sudo, ought to use sudo. In a shared
environment, this is typically not desirable (or possible), and
in that case you should set this variable to false
:use_sudo	true		

Sets the path to sudo.
:sudo				

variables are set via:
set :application, "flipper"


########## Interactive Shell ##########
      (requires capistrano-1.2.0)
Shell is essentially a SSH interface to your
servers, so you can run standard commands such 
as 'ls' or 'cp' as well as Capistrano-specific ones.

Start the interactive Capistrano shell
$ cap -v shell

Execute Capistrano tasks
cap> !deploy
cap> !update_code symlink
cap> !setup deploy
cap> on app2.foo.com !setup
cap> with app,db !setup deploy