[SOLVED] GNU Parallel combination of input parameters by index number

Issue

I know GNU Parallel is amazing at munching through all combinations of input parameters. I however have a script where I want the opposite, I have multiple arrays which I want to combine using a simple index.

This is what I have:

#!/bin/bash

letters='a b'
numbers='1 2'

f1(){
    echo $1 $2
    echo letter: $1
    echo number: $2
}
export -f f1

parallel f1 {1} {2} ::: $letters ::: $numbers

which gives:

a 1
letter: a
number: 1
a 2
letter: a
number: 2
b 1
letter: b
number: 1
b 2
letter: b
number: 2

I would just want to have this result though:

a 1
letter: a
number: 1
b 2
letter: b
number: 2

Any help appreciated, I didn't find an index switch in the (long) docs.

Solution

I think you just want to "link" your arguments:

parallel --link echo {1} {2} ::: 1 2 3 ::: a b c

Output

1 a
2 b
3 c

---

As opposed to:

parallel echo {1} {2} ::: 1 2 3 ::: a b c

which produces all permutations:

1 a
1 b
1 c
2 a
2 b
2 c
3 a
3 b
3 c

Answered By - Mark Setchell

Answer Checked By - Timothy Miller (WPSolving Admin)