Use lapply/for loop with system function for batch terminal commands

Question

I'm starting to the terminal more on my machine and would like to create a workflow where I have greater control over more repetitive tasks. My question is, can I use the system function, which takes a string and runs it through the terminal, within a loop? My hang up is looping over a string. My thought is to use the glue package, but I'm wondering if there is a base function for this or a better way than invoking an outside package?

library(glue)

setwd(path_to_files)
dir.create('pdf')

all_files <- list.files()

lapply(all_files, function(x){
  system('sytsunoconv -f [format] pdf  {x}.pptw')
})

Answer 1

Using system within an iterative loop shouldn't be a problem. To create a vector of commands you can use base R's paste or paste0, although glue can be useful when dealing with more complex strings.

Creating a vector of commands is as easy as paste("say", 1:5), which returns [1] "say 1" "say 2" "say 3" "say 4" "say 5". You can use it in a for loop with system to run each in sequence:

for (command in paste("say", 1:5)) {
    system(command)
}

If your on a Mac you should hear the TTS pronouncing each number.

You should be able to use the same pattern for your example, e.g.:

for (command in paste0('sytsunoconv -f [format] pdf ', list.files(), ".pptw")) {
    system(command)
}

Note that I use paste0 here to avoid unnecessary whitespace.