returnszero

Prototype: returnszero(command, shell)

Return type: boolean

The return value is cached.

Description: Runs command and returns whether it has returned with exit status zero.

This is the complement of execresult(), but it returns a class result rather than the output of the command.

Arguments:

• command: string, in the range: .+
• shell: one of
  • noshell
  • useshell
  • powershell

Example:

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

bundle agent example
{
  classes:

      "my_result" expression => returnszero("/usr/local/bin/mycommand","noshell");

  reports:

    !my_result::

      "Command failed";

}

Output:

2014-08-18T14:13:28+0100 error: Proposed executable file '/usr/local/bin/mycommand' doesn't exist
2014-08-18T14:13:28+0100 error: returnszero '/usr/local/bin/mycommand' is assumed to be executable but isn't
error: Proposed executable file '/usr/local/bin/mycommand' doesn't exist
error: returnszero '/usr/local/bin/mycommand' is assumed to be executable but isn't
R: Command failed

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. Effectively calls to this function will be also repeatedly executed by cf-promises when it does syntax checking, which is highly undesirable if the command is expensive. Consider using commands promises instead, which have locking and are not evaluated by cf-promises.

See also: execresult().