Array won't return ref value (bash)

Question

I've been trying to storage my data in an array as follows:

table="$1"
reference="$2"
directory="$3"

declare -A count

$reference | while read line; do
    ref=`echo $line | cut -d " " -f1`
    key=`echo $line | cut -d " " -f4`
    count=([$key]=$ref)
    echo $ref
    echo $key
    echo "${count[$key]}"
 done

This works, I do the prints and for each key I got the value I want. Then, I try to use with some keys:

cat $table | while read line; do
    sample=`echo $line | cut -d "_" -f1`
    id=${count[$line]}
    echo $sample
    echo $line
    echo $id
    echo "works"
done

Here is the problem: Sample is echoed perfectly, just as are $line and "works". But $id is not working, and I have no idea what I am missing here

P.P · Accepted Answer · 2015-12-02 17:41:06Z

1

That's because whatever you store in count are gone as soon as the subshell that runs the while loop exits. The while loop that you pipe into runs in a subshell. So any variables you "set" won't be available outside if it. That means when you later use count, it doesn't have any elements.

Change the loop to:

while IFS= read -r line; do
    ref=`echo $line | cut -d " " -f1`
    key=`echo $line | cut -d " " -f4`
    count["$key"]="$ref"
    echo $ref
    echo $key
    echo "${count[$key]}"
 done < "${reference}"

Similarly change in the other loop.

I am assuming reference is a file. If reference is actually the text you want to read the "lines" from then you can use here strings:

while IFS= read -r line; do
    ...
    ...  
done <<< "${reference}"

edited Dec 2, 2015 at 17:41

answered Dec 2, 2015 at 16:55

P.P

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10 Comments

MLMH Over a year ago

shouldn't declare -A count deal with that?

P.P Over a year ago

No. It just declares an array. It's not related to the issue. The count that's updated inside the loop is not same one you have outside. Inside the subshell, it's a different variable and doesn't exist once the subshell exits.

Etan Reisner Over a year ago

Not to mention that count=(...) is creating a new array each time and blowing up any old contents.

P.P Over a year ago

@EtanReisner Thanks for pointing it out. I didn't see it at all. I think, it should be fine now.

Etan Reisner Over a year ago

Yeah, that's not it. You want count+=(["$key"]="$ref") I believe.

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