You can use PDI's command line tools to execute PDI content from outside of the PDI client (Spoon). Typically you would use these tools in the context of creating a script or a cron job to run the job or transformation based on some condition outside of the realm of Pentaho software.
Pan is the PDI command line tool for executing transformations.
Kitchen is the PDI command line tool for executing jobs.
Both of these programs are explained in detail below.