Deprecation: run_command and popen4 helper method removal (OHAI-3)

Ohai ships a command mixin for use by plugin authors in shelling out to external commands. This mixin originally included run_command and popen4 methods, which were deprecated in Ohai 8.11.1 (Chef Infra Client 12.8.1) in favor of the more robust mixlib-shellout gem functionality. In Chef Infra Client 13 these deprecated methods will be removed, breaking any Ohai plugins authored using the deprecated methods.

Remediation

Plugins should be updated to use mixlib-shellout instead of the run_command.

Deprecated run_command based code:

status, stdout, stderr = run_command(command: 'myapp --version')
if status == 0
  version = stdout
end

Updated code for mixlib shellout:

so = shell_out('myapp --version')
if so.exitstatus == 0
  version = so.stdout
end

See the mixlib-shellout repo for additional usage information.