Return name of elasticbeanstalk environment based on keyword

getenv.sh

#!/usr/bin/env bash
REQ_ENV=$1

if [ $# -ne 1 ]
then
    echo "Autodetects the name of the desired elasticbeanstalk environment based on a keyword (e.g. staging)."
    echo " "
    echo "    Usage: getenv.sh [staging|prod]"
    exit 1
fi

# Return position of given string within another string
#
# @param string $1
#   Input string.
# @param string $2
#   String that will be searched in input string.
# @param int [$3]
#   Offset of an input string.
strpos()
{
    local str=${1}
    local offset=${3}

    if [ -n "${offset}" ]; then
        str=`substr "${str}" ${offset}`
    else
        offset=0
    fi

    str=${str/${2}*/}

    if [ "${#str}" -eq "${#1}" ]; then
        echo "false"
        return 0
    fi

    echo $((${#str}+${offset}))
}

ENV_LIST=("$(eb list)")

for ENV in "${ENV_LIST[@]}"
do
    RES="$(strpos "${ENV}" "${REQ_ENV}")"

    if [ $RES != "false" ]; then
        # get rid of star
        echo "${ENV//'* '}"
        exit 0
    fi
done

echo "No environment matching ${REQ_ENV} found."
exit 1