Store grep output in an array

You can use:

targets=($(grep -HRl "pattern" .))

Note use of (...) for array creation in BASH.

Also you can use grep -l to get only file names in grep's output (as shown in my command).

Above answer (written 7 years ago) made an assumption that output filenames won't contain special characters like whitespaces or globs. Here is a safe way to read those special filenames into an array: (will work with older bash versions)

while IFS= read -rd ''; do
   targets+=("$REPLY")
done < <(grep --null -HRl "pattern" .)

# check content of array
declare -p targets

On BASH 4+ you can use readarray instead of a loop:

readarray -d '' -t targets < <(grep --null -HRl "pattern" .)