run job script with different variables found in other files

Question

Let's suppose I have the following list of variables in a txt file (var.txt):

AAA
ABC
BBB
CCC

the following R script (script.R), where x is one variable in var.txt:

print(x)

and the following HPC slurm job script (job.sh):

#!/bin/bash
#SBATCH --job-name test
#SBATCH --ntasks 8
#SBATCH --time 04:00
#SBATCH --output out
#SBATCH --error err

Rscript script.R

How can I run the job.sh script 4 times in sequence, each time with a different variable inside script.R?

Expected output: 4 slurm jobs with script.R printing AAA, ABC, BBB, and CCC.

Answer 1

This is the typical workload suited for a job array. With a submission script like this

#!/bin/bash
#SBATCH --job-name test
#SBATCH --ntasks 8
#SBATCH --time 04:00
#SBATCH --output out
#SBATCH --error err
#SBATCH --array=0-3

readarray -t VARS < var.txt
VAR=${VARS[$SLURM_ARRAY_TASK_ID]}
export VAR

Rscript script.R

and script.R being

print(Sys.getenv("VAR"))

you will get a four-jobs job array, each one running the R script with a different value of the env var VAR, taken from the var.txt file.