There is nos such problem in ispconfig, as this all depends on the settings that you have choosen while you created the client in ispconfig. If you can run any binary as cronjob depends on your security settings. If you allow normal (not jailed) cronjobs in the client settings, then you can run your cronjob like you do it in cpanel. But ISPConfig has some more secure methods available for cronjobs like jailed cronjobs or url cronjobs which are active by default. You might want to take a look into the ispconfig manual which explains the different options.
I think i understood, and i'll try late today
Last question, please: there's no way, in ISPConfig, to make it runs cron jobs via the plugins i said, but without the need the user sets his own cron jobs in the panel?
I have (as client) two domains hosted in cPanel and Plesk, and i have no need to set any cron job in the panel. I activate the plugin, i schedule the backup, and it runs perfectly
Sorry again for my bad english. You know, i'm looking for a "idiot-proof" way to set backups for our clients that runs Wordpress