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Convert a String to an Array in Bash

and iterate over it​

Example Scenario​

In a situation where we receive a string that contains an array with a consistent delimeter we might want to iterate over that in order to perform some action.

Example array as a string input. We're assuming it's in this state because it was easy for the CI/CD tooling to pass in the array in this structure.

Example data structure​

TARGETS="email1@email.com, email2@email.com, email3@email.com"

In this case we want to iterate over each of those email addresses and send the person a message.

Ensure consistency​

Firstly, we want the string in a consistent state, we don't know if the input will include spaces or not so best we remove them.

TARGETS=$(echo "${TARGETS}" | tr -d ' ') # remove white space from targets array (currently a string)

We could also use a regex check to ensure that the email is a valid email but that's a bit overkill in this situation.

Convert the now clean string to an array of values​

IFS=',' read -r -a LIST_OF_TARGETS <<< "${TARGETS}" # convert the string into an array (comma delimeter)

What's happening here?​

  • We're setting the value separator (delimeter) with the IFS=',' portion.
  • We're creating an array called LIST_OF_TARGETS
  • We're reading through the TARGETS string splitting the values into elements of the array.

Loop the array (to do something)​

for CURRENT_TARGET in "${LIST_OF_TARGETS[@]}"
do  
    if sendMessage "Hello" "${CURRENT_TARGET}; then
        echo "Sent successfully"
    else
        echo "Message failed to send"
    fi
done