Class: SysCmd::Command

Inherits:
Object
  • Object
show all
Defined in:
lib/sys_cmd.rb

Overview

An executable system command

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(command, options = {}) ⇒ Command

Returns a new instance of Command.



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# File 'lib/sys_cmd.rb', line 177

def initialize(command, options = {})
  if command.respond_to?(:shell)
    @command = command.command
    @shell = command.shell
  else
    @command = command
    @shell = Shell.new(options)
  end
  @output = nil
  @status = nil
  @error_output = nil
  @error = nil
end

Instance Attribute Details

#command ⇒ Object (readonly)

Returns the value of attribute command.



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# File 'lib/sys_cmd.rb', line 191

def command
  @command
end

#error ⇒ Object (readonly)

Returns the value of attribute error.



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# File 'lib/sys_cmd.rb', line 191

def error
  @error
end

#error_output ⇒ Object (readonly)

Returns the value of attribute error_output.



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# File 'lib/sys_cmd.rb', line 191

def error_output
  @error_output
end

#output ⇒ Object (readonly)

Returns the value of attribute output.



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# File 'lib/sys_cmd.rb', line 191

def output
  @output
end

#status ⇒ Object (readonly)

Returns the value of attribute status.



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# File 'lib/sys_cmd.rb', line 191

def status
  @status
end

Instance Method Details

#error? ⇒ Boolean

did the command execution caused an exception?

Returns:

  • (Boolean) 


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# File 'lib/sys_cmd.rb', line 270

def error?
  !@error.nil?
end

#run(options = {}) ⇒ Object

Execute the command.

By default the command is executed by a shell. In this case, unquoted arguments are interpreted by the shell, e.g.

SysCmd.command('echo $BASH').run # /bin/bash

When the :direct option is set to true, no shell is used and the command is directly executed; in this case unquoted arguments are not interpreted:

SysCmd.command('echo $BASH').run # $BASH

The exit status of the command is retained in the status attribute (and its numeric value in the status_value attribute).

The standard output of the command is captured and retained in the output attribute.

By default, the standar error output of the command is not captured, so it will be shown on the console unless redirected.

Standard error can be captured and interleaved with the standard output passing the option

error_output: :mix

Error output can be captured and keep separate inthe error_output attribute with this option:

error_output: :separate

The value returned is by defaut, like in Kernel#system, true if the command gives zero exit status, false for non zero exit status, and nil if command execution fails.

The :return option can be used to make this method return other attribute of the executed command.



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# File 'lib/sys_cmd.rb', line 232

def run(options = {})
  @output = @status = @error_output = @error = nil
  if options[:direct]
    command = @shell.split(@command)
  else
    command = [@command]
  end
  begin
    case options[:error_output]
    when :mix # mix stderr with stdout
      @output, @status = Open3.capture2e(*command)
    when :separate
      @output, @error_output, @status = Open3.capture3(*command)
    else # :console (do not capture stderr output)
      @output, @status = Open3.capture2(*command)
    end
  rescue => error
    @error = error.dup
  end
  case options[:return]
  when :status
    @status
  when :status_value
    status_value
  when :output
    @output
  when :error_output
    @error_output
  else
    @error ? nil : @status.success? ? true : false
  end
end

#status_value ⇒ Object 



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# File 'lib/sys_cmd.rb', line 265

def status_value
  @status && @status.exitstatus
end

#success? ⇒ Boolean

did the command execute without error and returned a success status?

Returns:

  • (Boolean) 


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# File 'lib/sys_cmd.rb', line 275

def success?
  !error? && @status.success?
end

#to_s ⇒ Object 



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# File 'lib/sys_cmd.rb', line 279

def to_s
  command
end