Check if an element is in a list in POSIX shell

contains.sh

# Given a list represented as "element1 element2 element3 ..."
# Given an element
# This is a function that returns "yes" or "no" whether the list contains the string 

contains() {
    # $1 is the list
    # $2 is the element to look for
    if echo "$1" | grep -q "$2"; then
        echo "yes"
    else
        echo "no"
    fi
}


# Examples:
#
# contains "hello everyone" "hello" -> return "yes"
#
# contains "hello everyone" "goodbye" -> return "no"