Schedule R scripts/processes with the cron scheduler. This allows R users working on Unix/Linux to automate R processes at specific timepoints from R itself. Note that if you are looking for a Windows scheduler, you might be interested in the R package taskscheduleR available at https://github.com/bnosac/taskscheduleR

This R package allows you to

• Get the list of scheduled jobs
• Remove scheduled jobs
• Add a job
  • A job is basically a script with R code which is run through Rscript
  • You can schedule tasks 'ONCE', 'EVERY MINUTE', 'EVERY HOUR', 'EVERY DAY', 'EVERY WEEK', 'EVERY MONTH' or any complex schedule
  • The task log contains the stdout & stderr of the Rscript which was run on that timepoint. This log can be found at the same folder as the R script

The package also contains an RStudio addin. If you install the package and use RStudio version 0.99.893 or later you can just click to schedule a task. Just click Addins > Schedule R scripts on Linux/Unix.

• Alternatively, run cronR::cron_rstudioaddin() to open the addin interface. If you use that addin to schedule scripts, by default it will copy the R scripts to your current working directory and launch the copied scripts from there. A different directory can be specified by passing an argument to the RscriptRepository parameter cronR::cron_rstudioaddin(RscriptRepository = "/path/to/your/deployment/directory")
• You can also set the CRON_LIVE environment variable to specify a default directory to copy scheduled scripts to. This can be done by putting something like CRON_LIVE="/path/to/your/deployment/directory" in your .Renviron or .Rprofile file. See ?Startup

Some example use cases are shown below, indicating to schedule a script at specific timepoints.

library(cronR)
f   <- system.file(package = "cronR", "extdata", "helloworld.R")
cmd <- cron_rscript(f)
cmd

cron_add(command = cmd, frequency = 'minutely', id = 'test1', description = 'My process 1', tags = c('lab', 'xyz'))
cron_add(command = cmd, frequency = 'daily', at='7AM', id = 'test2')
cron_njobs()

cron_ls()
cron_clear(ask = TRUE)
cron_ls()

cmd <- cron_rscript(f, rscript_args = c("productx", "arg2", "123"))
cmd
cron_add(cmd, frequency = 'minutely', id = 'job1', description = 'Customers')
cron_add(cmd, frequency = 'hourly', id = 'job2', description = 'Weather')
cron_add(cmd, frequency = 'hourly', id = 'job3', days_of_week = c(1, 2))
cron_add(cmd, frequency = 'hourly', id = 'job4', at = '00:20', days_of_week = c(1, 2))
cron_add(cmd, frequency = 'daily', id = 'job5', at = '14:20')
cron_add(cmd, frequency = 'daily', id = 'job6', at = '14:20', days_of_week = c(0, 3, 5))
cron_add(cmd, frequency = 'daily', id = 'job7', at = '23:59', days_of_month = c(1, 30))
cron_add(cmd, frequency = 'monthly', id = 'job8', at = '10:30', days_of_month = 'first', days_of_week = '*')
cron_add(cmd, frequency = '@reboot', id = 'job9', description = 'Good morning')
cron_add(cmd, frequency = '*/15 * * * *', id = 'job10', description = 'Every 15 min')   
cron_ls()
cron_clear(ask = TRUE)

By default, when you use the functions cron_add, cron_rm, cron_clear, cron_load, a prompt will ask for your permission to update the cron schedule, unless you put the argument ask=FALSE in each of these functions, in which case you automatically allow to update the schedule. (new since R package version 0.6.0)

Make sure the cron daemon (https://en.wikipedia.org/wiki/Cron) is running. On Debian this is done as follows.

sudo apt-get update
sudo apt-get install -y cron
sudo cron start

• For regular users, install the package from your local CRAN mirror with install.packages("cronR"), for installing the development version of this package: remotes::install_github("bnosac/cronR")
• If you want the RStudio add-in to work, also install miniUI, shiny and shinyFiles

install.packages("cronR")
install.packages('miniUI')
install.packages('shiny')
install.packages('shinyFiles')

Now have a look at ?cron_add or start the RStudio addin

• Consider adding options(echo = TRUE) at the start of your R scripts in order to debug your scripts in case of errors.
• Consider using argument env when calling cron_add if you need specific environment variables to be used in your script, These will be prepended to your script. E.g. as follows where you replace dry_run to FALSE to add it to your cron job list.

cmd <- cron_rscript("/path/to/your/script.R")
cron_add(cmd, frequency = 'minutely', id = 'job1', description = 'Customers', 
         env = c(LANG = "en_US.UTF-8", R_LIBS_USER = Sys.getenv("R_LIBS_USER"), YOUR_PROJECT_XYZ = getwd()), 
         ask = FALSE, dry_run = TRUE)

• Currently, cronR does not preserve or handle cron jobs not generated through the package. This will be handled some time in the future. To be safe, you should run cron_save("cron.backup") before fiddling around.