Class: Mixlib::ShellOut

Inherits:
Object
  • Object
show all
Includes:
Unix, Windows
Defined in:
lib/mixlib/shellout.rb,
lib/mixlib/shellout/unix.rb,
lib/mixlib/shellout/version.rb,
lib/mixlib/shellout/windows.rb,
lib/mixlib/shellout/exceptions.rb

Defined Under Namespace

Modules: Unix, Windows Classes: CommandTimeout, EmptyWindowsCommand, Error, InvalidCommandOption, ShellCommandFailed

Constant Summary

READ_WAIT_TIME =
0.01
READ_SIZE =
4096
DEFAULT_READ_TIMEOUT =
600
VERSION =
"2.3.2"

Constants included from Unix

Unix::ONE_DOT_EIGHT_DOT_SEVEN

Constants included from Windows

Windows::TIME_SLICE

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Unix

#all_seconderies, #logon_environment, #process_environment, #sgids, #using_login?

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.

  • 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 600 seconds. Note: the stdlib Timeout library is not used.

  • input: A String of data to be passed to the subcommand. This is written to the child process' stdin stream before the process is launched. The child's stdin stream will be a pipe, so the size of input data should not exceed the system's default pipe capacity (4096 bytes is a safe value, though on newer Linux systems the capacity is 64k by default).

  • live_stream: An IO or Logger-like object (must respond to the append operator <<) that will receive data as ShellOut reads it from the child process. Generally this is used to copy data from the child to the parent's stdout so that users may observe the progress of long-running commands.

  • login: Whether to simulate a login (set secondary groups, primary group, environment variables etc) as done by the OS in an actual login

Examples:

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

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


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# File 'lib/mixlib/shellout.rb', line 167

def initialize(*command_args)
  @stdout, @stderr, @process_status = "", "", ""
  @live_stdout = @live_stderr = nil
  @input = nil
  @log_level = :debug
  @log_tag = nil
  @environment = {}
  @cwd = nil
  @valid_exit_codes = [0]
  @terminate_reason = nil
  @timeout = nil
  @elevated = false

  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

#commandObject (readonly)

The command to be executed.



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# File 'lib/mixlib/shellout.rb', line 84

def command
  @command
end

#cwdObject

Working directory for the subprocess. Normally set via options to new



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# File 'lib/mixlib/shellout.rb', line 54

def cwd
  @cwd
end

#domainObject

Returns the value of attribute domain



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# File 'lib/mixlib/shellout.rb', line 41

def domain
  @domain
end

#elevatedObject

Runs windows process with elevated privileges. Required for Powershell commands which need elevated privileges



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# File 'lib/mixlib/shellout.rb', line 113

def elevated
  @elevated
end

#environmentObject

Environment variables that will be set for the subcommand. Refer to the documentation of new to understand how ShellOut interprets this.



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# File 'lib/mixlib/shellout.rb', line 91

def environment
  @environment
end

#execution_timeObject (readonly)

The amount of time the subcommand took to execute



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# File 'lib/mixlib/shellout.rb', line 98

def execution_time
  @execution_time
end

#groupObject

Group the command will run as. Normally set via options passed to new



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# File 'lib/mixlib/shellout.rb', line 51

def group
  @group
end

#inputObject

ShellOut will push data from :input down the stdin of the subprocss. Normally set via options passed to new. Default: nil



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# File 'lib/mixlib/shellout.rb', line 71

def input
  @input
end

#live_stderrObject

When live_stderr is set, the stderr of the subprocess will be copied to it as the subprocess is running.



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# File 'lib/mixlib/shellout.rb', line 66

def live_stderr
  @live_stderr
end

#live_stdoutObject

When live_stdout is set, the stdout of the subprocess will be copied to it as the subprocess is running.



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# File 'lib/mixlib/shellout.rb', line 62

def live_stdout
  @live_stdout
end

#log_levelObject

The log level at which ShellOut should log.



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# File 'lib/mixlib/shellout.rb', line 78

def log_level
  @log_level
end

#log_tagObject

A string which will be prepended to the log message.



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# File 'lib/mixlib/shellout.rb', line 81

def log_tag
  @log_tag
end

#loggerObject

If a logger is set, ShellOut will log a message before it executes the command.



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# File 'lib/mixlib/shellout.rb', line 75

def logger
  @logger
end

#loginObject

Whether to simulate logon as the user. Normally set via options passed to new Always enabled on windows



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# File 'lib/mixlib/shellout.rb', line 48

def 
  @login
end

#passwordObject

Returns the value of attribute password



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# File 'lib/mixlib/shellout.rb', line 42

def password
  @password
end

#process_status_pipeObject (readonly)

Returns the value of attribute process_status_pipe



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# File 'lib/mixlib/shellout.rb', line 110

def process_status_pipe
  @process_status_pipe
end

#statusObject (readonly)

A Process::Status (or ducktype) object collected when the subprocess is reaped.



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# File 'lib/mixlib/shellout.rb', line 108

def status
  @status
end

#stderrObject (readonly)

Data written to stderr by the subprocess



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# File 'lib/mixlib/shellout.rb', line 104

def stderr
  @stderr
end

#stderr_pipeObject (readonly)

Returns the value of attribute stderr_pipe



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# File 'lib/mixlib/shellout.rb', line 110

def stderr_pipe
  @stderr_pipe
end

#stdin_pipeObject (readonly)

Returns the value of attribute stdin_pipe



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# File 'lib/mixlib/shellout.rb', line 110

def stdin_pipe
  @stdin_pipe
end

#stdoutObject (readonly)

Data written to stdout by the subprocess



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# File 'lib/mixlib/shellout.rb', line 101

def stdout
  @stdout
end

#stdout_pipeObject (readonly)

Returns the value of attribute stdout_pipe



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# File 'lib/mixlib/shellout.rb', line 110

def stdout_pipe
  @stdout_pipe
end

#timeoutObject



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# File 'lib/mixlib/shellout.rb', line 222

def timeout
  @timeout || DEFAULT_READ_TIMEOUT
end

#umaskObject

The umask that will be set for the subcommand.



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# File 'lib/mixlib/shellout.rb', line 87

def umask
  @umask
end

#userObject

User the command will run as. Normally set via options passed to new



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# File 'lib/mixlib/shellout.rb', line 40

def user
  @user
end

#valid_exit_codesObject

An Array of acceptable exit codes. #error? (and #error!) use this list to determine if the command was successful. Normally set via options to new



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# File 'lib/mixlib/shellout.rb', line 58

def valid_exit_codes
  @valid_exit_codes
end

#with_logonObject

TODO remove



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# File 'lib/mixlib/shellout.rb', line 44

def with_logon
  @with_logon
end

Instance Method Details

#error!Object

If #error? is true, calls invalid!, which raises an Exception.

Returns

nil:

always returns nil when it does not raise

Raises

::ShellCommandFailed:

via invalid!



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# File 'lib/mixlib/shellout.rb', line 279

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

#error?Boolean

Checks the exitstatus against the set of valid_exit_codes.

Returns

true if exitstatus is not in the list of valid_exit_codes, false otherwise.



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# File 'lib/mixlib/shellout.rb', line 270

def error?
  !Array(valid_exit_codes).include?(exitstatus)
end

#exitstatusObject

The exit status of the subprocess. Will be nil if the command is still running or died without setting an exit status (e.g., terminated by `kill -9`).



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# File 'lib/mixlib/shellout.rb', line 243

def exitstatus
  @status && @status.exitstatus
end

#format_for_exceptionObject

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/mixlib/shellout.rb', line 229

def format_for_exception
  msg = ""
  msg << "#{@terminate_reason}\n" if @terminate_reason
  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

#gidObject

The gid that the subprocess will switch to. If the group attribute is given as a group name, it is converted to a gid by Etc.getgrnam TODO migrate to shellout/unix.rb



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# File 'lib/mixlib/shellout.rb', line 216

def gid
  return group.kind_of?(Integer) ? group : Etc.getgrnam(group.to_s).gid if group
  return Etc.getpwuid(uid).gid if using_login?
  nil
end

#inspectObject



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# File 'lib/mixlib/shellout.rb', line 296

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 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

ShellCommandFailed always

Raises:



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# File 'lib/mixlib/shellout.rb', line 291

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

#live_streamObject

Returns the stream that both is being used by both live_stdout and live_stderr, or nil



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# File 'lib/mixlib/shellout.rb', line 188

def live_stream
  live_stdout == live_stderr ? live_stdout : nil
end

#live_stream=(stream) ⇒ Object

A shortcut for setting both live_stdout and live_stderr, so that both the stdout and stderr from the subprocess will be copied to the same stream as the subprocess is running.



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# File 'lib/mixlib/shellout.rb', line 195

def live_stream=(stream)
  @live_stdout = @live_stderr = stream
end

#run_commandObject

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)

  • CommandTimeout when the command does not complete within timeout seconds (default: 600s)



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# File 'lib/mixlib/shellout.rb', line 258

def run_command
  if logger
    log_message = (log_tag.nil? ? "" : "#{@log_tag} ") << "sh(#{@command})"
    logger.send(log_level, log_message)
  end
  super
end

#uidObject

The uid that the subprocess will switch to. If the user attribute was given as a username, it is converted to a uid by Etc.getpwnam TODO migrate to shellout/unix.rb



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# File 'lib/mixlib/shellout.rb', line 208

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