How can i replace variables inside quotation marks in parallel

Question

I want to run on parallel a command that inputs two variables into a gnuplot file, I tried with:

parallel 'OMP_NUM_THREADS=11 gnuplot -e 'alpha={}; file="{}.txt"' graf_separation_time.gp' ::: 0 1 2 3 4 5 6 7 8 9 10 

But it doesn't work, any suggestions?

Answer 1

You are being hit by using ' inside '. Quoting is hard to get right, so it is often easier to define a function, test it and then have GNU Parallel call that.

Untested:

gp() {
  OMP_NUM_THREADS=11 gnuplot -e 'alpha='"$1"'; file="'"$1"'.txt" graf_separation_time.gp'
}
export -f gp
parallel gp {} ::: 0 1 2 3 4 5 6 7 8 9 10 

This will probably also work:

parallel -q OMP_NUM_THREADS=11 gnuplot -e 'alpha={}; file="{}.txt" graf_separation_time.gp' ::: 0 1 2 3 4 5 6 7 8 9 10 

Read more: https://www.gnu.org/software/parallel/man.html#quoting