Class: Chef::ShellOut

Inherits:
Object show all
Includes:
Unix, Windows
Defined in:
lib/chef/shell_out.rb,
lib/chef/shell_out/unix.rb,
lib/chef/shell_out/windows.rb

Overview

Chef::ShellOut

Provides a simplified interface to shelling out yet still collecting both standard out and standard error and providing full control over environment, working directory, uid, gid, etc.

No means for passing input to the subprocess is provided, nor is there any way to inspect the output of the command as it is being read. If you need to do that, you have to use popen4 (in Chef::Mixin::Command)

Platform Support

Chef::ShellOut uses Kernel.fork() and is therefore unsuitable for Windows or jruby.

Defined Under Namespace

Modules: Unix, Windows

Constant Summary collapse

READ_WAIT_TIME = 
0.01
READ_SIZE = 
4096
DEFAULT_READ_TIMEOUT = 
600
DEFAULT_ENVIRONMENT = 
{'LC_ALL' => 'C'}

Constants included from Windows

Windows::TIME_SLICE

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*command_args) ⇒ ShellOut

Arguments:

Takes a single command, or a list of command fragments. These are used as arguments to Kernel.exec. See the Kernel.exec documentation for more explanation of how arguments are evaluated. The last argument can be an options Hash.

Options:

If the last argument is a Hash, it is removed from the list of args passed to exec and used as an options hash. The following options are available:

  • user: the user the commmand should run as. if an integer is given, it is used as a uid. A string is treated as a username and resolved to a uid with Etc.getpwnam

  • group: the group the command should run as. works similarly to user

  • cwd: the directory to chdir to before running the command

  • umask: a umask to set before running the command. If given as an Integer, be sure to use two leading zeros so it’s parsed as Octal. A string will be treated as an octal integer

  • returns: one or more Integer values to use as valid exit codes for the subprocess. This only has an effect if you call error! after run_command.

  • environment: a Hash of environment variables to set before the command is run. By default, the environment will always be set to ‘LC_ALL’ => ‘C’ to prevent issues with multibyte characters in Ruby 1.8. To avoid this, use :environment => nil for no extra environment settings, or :environment => … to set other environment settings without changing the locale.

  • timeout: a Numeric value for the number of seconds to wait on the child process before raising an Exception. This is calculated as the total amount of time that ShellOut waited on the child process without receiving any output (i.e., IO.select returned nil). Default is 60 seconds. Note: the stdlib Timeout library is not used.

Examples:

Invoke find(1) to search for .rb files:

find = Chef::ShellOut.new("find . -name '*.rb'")
find.run_command
# If all went well, the results are on +stdout+
puts find.stdout
# find(1) prints diagnostic info to STDERR:
puts "error messages" + find.stderr
# Raise an exception if it didn't exit with 0
find.error!

Run a command as the www user with no extra ENV settings from /tmp

cmd = Chef::ShellOut.new("apachectl", "start", :user => 'www', :env => nil, :cwd => '/tmp')
cmd.run_command # etc.



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# File 'lib/chef/shell_out.rb', line 112

def initialize(*command_args)
  @stdout, @stderr = '', ''
  @live_stream = nil
  @command_log_level = :debug
  @command_log_prepend = nil 
  @environment = DEFAULT_ENVIRONMENT
  @cwd = nil
  @valid_exit_codes = [0]

  if command_args.last.is_a?(Hash)
    parse_options(command_args.pop)
  end

  @command = command_args.size == 1 ? command_args.first : command_args
end

Instance Attribute Details

#command ⇒ Object (readonly)

Returns the value of attribute command.



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# File 'lib/chef/shell_out.rb', line 61

def command
  @command
end

#command_log_level ⇒ Object

Returns the value of attribute command_log_level.



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# File 'lib/chef/shell_out.rb', line 58

def command_log_level
  @command_log_level
end

#command_log_prepend ⇒ Object

Returns the value of attribute command_log_prepend.



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# File 'lib/chef/shell_out.rb', line 59

def command_log_prepend
  @command_log_prepend
end

#cwd ⇒ Object

Returns the value of attribute cwd.



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# File 'lib/chef/shell_out.rb', line 55

def cwd
  @cwd
end

#environment ⇒ Object (readonly)

Returns the value of attribute environment.



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# File 'lib/chef/shell_out.rb', line 61

def environment
  @environment
end

#execution_time ⇒ Object (readonly)

Returns the value of attribute execution_time.



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# File 'lib/chef/shell_out.rb', line 63

def execution_time
  @execution_time
end

#group ⇒ Object

Returns the value of attribute group.



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# File 'lib/chef/shell_out.rb', line 54

def group
  @group
end

#live_stream ⇒ Object

Returns the value of attribute live_stream.



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# File 'lib/chef/shell_out.rb', line 57

def live_stream
  @live_stream
end

#process_status_pipe ⇒ Object (readonly)

Returns the value of attribute process_status_pipe.



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# File 'lib/chef/shell_out.rb', line 67

def process_status_pipe
  @process_status_pipe
end

#status ⇒ Object (readonly)

Returns the value of attribute status.



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# File 'lib/chef/shell_out.rb', line 65

def status
  @status
end

#stderr ⇒ Object (readonly)

Returns the value of attribute stderr.



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# File 'lib/chef/shell_out.rb', line 65

def stderr
  @stderr
end

#stderr_pipe ⇒ Object (readonly)

Returns the value of attribute stderr_pipe.



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# File 'lib/chef/shell_out.rb', line 67

def stderr_pipe
  @stderr_pipe
end

#stdin_pipe ⇒ Object (readonly)

Returns the value of attribute stdin_pipe.



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# File 'lib/chef/shell_out.rb', line 67

def stdin_pipe
  @stdin_pipe
end

#stdout ⇒ Object (readonly)

Returns the value of attribute stdout.



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# File 'lib/chef/shell_out.rb', line 65

def stdout
  @stdout
end

#stdout_pipe ⇒ Object (readonly)

Returns the value of attribute stdout_pipe.



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# File 'lib/chef/shell_out.rb', line 67

def stdout_pipe
  @stdout_pipe
end

#timeout ⇒ Object 



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# File 'lib/chef/shell_out.rb', line 142

def timeout
  @timeout || DEFAULT_READ_TIMEOUT
end

#umask ⇒ Object

Returns the value of attribute umask.



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# File 'lib/chef/shell_out.rb', line 61

def umask
  @umask
end

#user ⇒ Object

Returns the value of attribute user.



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# File 'lib/chef/shell_out.rb', line 53

def user
  @user
end

#valid_exit_codes ⇒ Object

Returns the value of attribute valid_exit_codes.



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# File 'lib/chef/shell_out.rb', line 56

def valid_exit_codes
  @valid_exit_codes
end

Instance Method Details

#error! ⇒ Object

Checks the exitstatus against the set of valid_exit_codes. If exitstatus is not in the list of valid_exit_codes, calls invalid!, which raises an Exception.

Returns

nil:

always returns nil when it does not raise

Raises

Chef::Exceptions::ShellCommandFailed:

via invalid!



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# File 'lib/chef/shell_out.rb', line 190

def error!
  unless Array(valid_exit_codes).include?(exitstatus)
    invalid!("Expected process to exit with #{valid_exit_codes.inspect}, but received '#{exitstatus}'")
  end
end

#exitstatus ⇒ Object 



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# File 'lib/chef/shell_out.rb', line 159

def exitstatus
  @status && @status.exitstatus
end

#format_for_exception ⇒ Object

Creates a String showing the output of the command, including a banner showing the exact command executed. Used by invalid! to show command results when the command exited with an unexpected status.



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# File 'lib/chef/shell_out.rb', line 149

def format_for_exception
  msg = ""
  msg << "---- Begin output of #{command} ----\n"
  msg << "STDOUT: #{stdout.strip}\n"
  msg << "STDERR: #{stderr.strip}\n"
  msg << "---- End output of #{command} ----\n"
  msg << "Ran #{command} returned #{status.exitstatus}" if status
  msg
end

#gid ⇒ Object 



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# File 'lib/chef/shell_out.rb', line 137

def gid
  return nil unless group
  group.kind_of?(Integer) ? group : Etc.getgrnam(group.to_s).gid
end

#inspect ⇒ Object 



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# File 'lib/chef/shell_out.rb', line 209

def inspect
  "<#{self.class.name}##{object_id}: command: '#@command' process_status: #{@status.inspect} " +
  "stdout: '#{stdout.strip}' stderr: '#{stderr.strip}' child_pid: #{@child_pid.inspect} " +
  "environment: #{@environment.inspect} timeout: #{timeout} user: #@user group: #@group working_dir: #@cwd >"
end

#invalid!(msg = nil) ⇒ Object

Raises a Chef::Exceptions::ShellCommandFailed exception, appending the command’s stdout, stderr, and exitstatus to the exception message.

Arguments

msg: A String to use as the basis of the exception message. The default explanation is very generic, providing a more informative message is highly encouraged.

Raises

Chef::Exceptions::ShellCommandFailed always

Raises:



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# File 'lib/chef/shell_out.rb', line 204

def invalid!(msg=nil)
  msg ||= "Command produced unexpected results"
  raise Chef::Exceptions::ShellCommandFailed, msg + "\n" + format_for_exception
end

#run_command ⇒ Object

Run the command, writing the command’s standard out and standard error to stdout and stderr, and saving its exit status object to status

Returns

returns self; stdout, stderr, status, and exitstatus will be populated with results of the command

Raises

  • Errno::EACCES when you are not privileged to execute the command

  • Errno::ENOENT when the command is not available on the system (or not in the current $PATH)

  • Chef::Exceptions::CommandTimeout when the command does not complete within timeout seconds (default: 60s)



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# File 'lib/chef/shell_out.rb', line 174

def run_command
  if command_log_prepend
    Chef::Log.send(command_log_level, "#{command_log_prepend} sh(#{@command})")
  else
    Chef::Log.send(command_log_level, "sh(#{@command})")
  end
  super
end

#uid ⇒ Object 



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# File 'lib/chef/shell_out.rb', line 132

def uid
  return nil unless user
  user.kind_of?(Integer) ? user : Etc.getpwnam(user.to_s).uid
end