Pass bash array to stdin

Question

I currently have a bash script like this, which successfully calls the program prog :

#!/bin/bash
var1=hello
var2=world
prog <<EOF
$var1
$var2
EOF

Instead of var1 and var2 , how would I pass each element within an array (of unknown length, since I am using $@) to prog in the same manner?

Answer 1

Strictly speaking, you would want something like

for line in "$@"; do
    echo "$line"
done | prog

It's not a here document, but it has the same effect. Here documents and arrays were developed for two different use cases.

Even more strictly speaking, $@ is not an array, although it tries very hard to behave like one. :)

Answer 2

You could loop over each element of the array and echo each value into the program:

vars=('foo' 'foo bar' 'bar')
for var in "${vars[@]}"; do echo $var; done | prog

FAIRNESS UPDATE : @chepner beat me to this answer by a few seconds :)

Answer 3

As far as I know, you cannot pass variables , but you can pass arguments , so here's a fix:

prog $VAR1 $VAR2 <<EOF

And inside prog you could use:

ARR=($@)

to save all the positional parameters to the variable ARR .