cron_add                Make a simple cron job
cron_clear              Clear all cron jobs
cron_load               Load a crontab from file
cron_ls                 List the contents of a crontab
cron_njobs              List the number of rCron cron jobs
cron_rm                 Remove a cronjob
cron_rscript            Create a command to execute an R script which
                        can be scheduled with cron_add
cron_rstudioaddin       Launch an RStudio addin which allows to
                        schedule an Rscript interactively.
cron_save               Save the current crontab
