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Mixlib::ShellOut

Attributes

command[R]

The command to be executed.

cwd[RW]

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

domain[RW]
environment[R]

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

execution_time[R]

The amount of time the subcommand took to execute

group[RW]

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

input[RW]

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

live_stream[RW]

When live_stream is set, stdout of the subprocess will be copied to it as the subprocess is running. For example, if live_stream is set to STDOUT, the command's output will be echoed to STDOUT.

log_level[RW]

The log level at which ShellOut should log.

log_tag[RW]

A string which will be prepended to the log message.

logger[RW]

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

password[RW]
process_status_pipe[R]
status[R]

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

stderr[R]

Data written to stderr by the subprocess

stderr_pipe[R]
stdin_pipe[R]
stdout[R]

Data written to stdout by the subprocess

stdout_pipe[R]
timeout[W]

The maximum time this command is allowed to run. Usually set via options to new

umask[R]

The umask that will be set for the subcommand.

user[RW]

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

valid_exit_codes[RW]

An Array of acceptable exit codes. error! uses this list to determine if the command was successful. Normally set via options to new

with_logon[RW]

Public Class Methods

new(*command_args) click to toggle source

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 => {'LC_ALL'=>nil, ...} 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 = 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.
# File lib/mixlib/shellout.rb, line 148
def initialize(*command_args)
  @stdout, @stderr = '', ''
  @live_stream = nil
  @input = nil
  @log_level = :debug
  @log_tag = 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

Public Instance Methods

error!() click to toggle source

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

::ShellCommandFailed:

via invalid!

# File lib/mixlib/shellout.rb, line 235
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() click to toggle source

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`).

# File lib/mixlib/shellout.rb, line 205
def exitstatus
  @status && @status.exitstatus
end
format_for_exception() click to toggle source

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.

# File lib/mixlib/shellout.rb, line 192
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() click to toggle source

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

# File lib/mixlib/shellout.rb, line 180
def gid
  return nil unless group
  group.kind_of?(Integer) ? group : Etc.getgrnam(group.to_s).gid
end
inspect() click to toggle source
# File lib/mixlib/shellout.rb, line 254
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) click to toggle source

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

# File lib/mixlib/shellout.rb, line 249
def invalid!(msg=nil)
  msg ||= "Command produced unexpected results"
  raise ShellCommandFailed, msg + "\n" + format_for_exception
end
run_command() click to toggle source

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)

# File lib/mixlib/shellout.rb, line 220
def run_command
  if logger
    log_message = (log_tag.nil? ? "" : "#@log_tag ") << "sh(#@command)"
    logger.send(log_level, log_message)
  end
  super
end
timeout() click to toggle source
# File lib/mixlib/shellout.rb, line 185
def timeout
  @timeout || DEFAULT_READ_TIMEOUT
end
uid() click to toggle source

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

# File lib/mixlib/shellout.rb, line 173
def uid
  return nil unless user
  user.kind_of?(Integer) ? user : Etc.getpwnam(user.to_s).uid
end
umask=(new_umask) click to toggle source

Set the umask that the subprocess will have. If given as a string, it will be converted to an integer by String#oct.

# File lib/mixlib/shellout.rb, line 167
def umask=(new_umask)
  @umask = (new_umask.respond_to?(:oct) ? new_umask.oct : new_umask.to_i) & 007777
end

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