execresult

Prototype: execresult(command, shell)

Return type: string

Description: Execute command and return output as string.

If the command is not found, the result will be the empty string.

Arguments:

  • command : Fully qualified command path, in the range "?(/.*)
  • shell : Shell encapsulation option, in the range useshell,noshell

Decides whether a shell will be used to encapsulate the command. This is necessary in order to combine commands with pipes etc, but remember that each command requires a new process that reads in files beyond CFEngine's control. Thus using a shell is both a performance hog and a potential security issue.

Example:

body common control
{
bundlesequence  => { "example" };
}

bundle agent example

{     
vars:

  "my_result" string => execresult("/bin/ls /tmp","noshell");

reports:

  linux::

    "Variable is $(my_result)";

}

Notes: you should never use this function to execute commands that make changes to the system, or perform lengthy computations. Such an operation is beyond CFEngine's ability to guarantee convergence, and on multiple passes and during syntax verification these function calls are executed, resulting in system changes that are 'covert'. Calls to execresult should be for discovery and information extraction only.

Change: policy change in CFEngine 3.0.5. Previously newlines were changed for spaces, now newlines are preserved.

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