Including more commands if CSV column is not empty

Let's say I have the following CSV file (sample.csv)

filepath1
filepath1,filepath2
filepath1,filepath2,filepath3
filepath1,filepath2,filepath3,filepath4
filepath1,filepath2

And the program I need to use uses the following syntax:

program_im_using --file filepath1

But if multiple files are present, the syntax for input is:

program_im_using --file filepath1 --file filepath2
or
program_im_using --file filepath1 --file filepath2 --file filepath3

What I would do to paste the values from the CSV file would be something like this:

filepath_first=( $(awk -F "\"*,\"*" '{print $1}' $sample_csv) )
filepath_second=( $(awk -F "\"*,\"*" '{print $2}' $sample_csv) )

for i in "${!filenames[@]}"; do
    program_im_using --file "${filepath_first[i]}" --file "${filepath_second[i]}"
done

My example of what I'm doing only works if I have exactly 2 columns of values in every row. How can I generalize in a way such that if I have one column, I get:

program_im_using --file filepath1

But if I have two

program_im_using --file filepath1 --file filepath2

etc?

Solution

For a variable number of args one common approach is to store the args in an array, eg:

$ args=(--file filepath1 --file filepath2)
$ typeset -p args
declare -a args=([0]="--file" [1]="filepath1" [2]="--file" [3]="filepath2")

A sample script to list input args:

$ cat program_im_using
#!/bin/bash
n=1
for i in "$@"; do echo "arg #$n:$i:";((n++));  done

We can then feed these args to the program like such:

$ ./program_im_using "${args[@]}"
arg #1 :--file:
arg #2 :filepath1:
arg #3 :--file:
arg #4 :filepath2:

Sample input file:

$ cat sample.csv
filepath1
filepath1,filepath2
filepath1,filepath2,filepath3
/a/b/c.txt,/d/e/f/g.txt,/h.txt

Using sed to reformat our csv lines:

$ sed 's/^/--file /; s/,/ --file /g' sample.csv
--file filepath1
--file filepath1 --file filepath2
--file filepath1 --file filepath2 --file filepath3
--file /a/b/c.txt --file /d/e/f/g.txt --file /h.txt

Feeding the sed results to a bash/while-read loop:

while read -ra args
do
    printf "\n####### ${args[*]}\n"
    ./program_im_using "${args[@]}"
done < <(sed 's/^/--file /; s/,/ --file /g' sample.csv)

NOTES:

OP has stated in comments that we do not need to worry about spaces or special characters in the csv fields otherwise ...
this approach will fail if the csv fields contain (white)space or characters that have a special meaning to bash

This generates:

####### --file filepath1
arg #1 :--file:
arg #2 :filepath1:

####### --file filepath1 --file filepath2
arg #1 :--file:
arg #2 :filepath1:
arg #3 :--file:
arg #4 :filepath2:

####### --file filepath1 --file filepath2 --file filepath3
arg #1 :--file:
arg #2 :filepath1:
arg #3 :--file:
arg #4 :filepath2:
arg #5 :--file:
arg #6 :filepath3:

####### --file /a/b/c.txt --file /d/e/f/g.txt --file /h.txt
arg #1 :--file:
arg #2 :/a/b/c.txt:
arg #3 :--file:
arg #4 :/d/e/f/g.txt:
arg #5 :--file:
arg #6 :/h.txt: