Terminal commands, periodic etc

There periodic housekeeping tasks are run automatically as needed by the operating system when the machine first boots in the morning, or at 3am if already running. In the Terminal, you can:

man periodic

and read what each of these launchd shell scripts perform.

Although you can run them individually from the command-line, this would be redundant, as they would have already run.

These are “maintenance” scripts that your system runs er... periodically - as each of their names indicates.

There is usually no reason for the user to run them manually.

In the old days (several versions ago) one might want to do this because these scripts were sometimes not run if the system happened to be sleeping at their scheduled time (which was often the case, since they were to be run at 3am or so). Not anymore. They are run at the first opportunity at or after their scheduled time.