Attempt at implementing Powershell's select using bash

select.sh

#!/usr/bin/env bash

usage() {
    echo "Usage: ${0/*\//} [OPTIONS]"
    echo "Options:"
    echo "    -d, --delimiter=DELIM"
    echo "        Use the specified delimiter (default: space)"
    echo "    -h, --help"
    echo "        Display this help message"
    echo
    echo "Empty fields or fields with DELIM in them will look weird"
    echo "or even break. If DELIM is space, only the last column can"
    echo "have spaces."
    echo
    exit $1
}

DELIM=" "
for arg in $@; do
    case "$STORE" in
        "delim") DELIM="$arg"
            ;;
    esac
    [ "$STORE" ] && unset STORE && continue

    case "$arg" in
        "-d"|"--delimiter") STORE="delim"
            ;;
        "-h"|"--help") usage 0
            ;;
        *) ARGS="$ARGS $arg"
            ;;
    esac
done
set -- $ARGS

[ "$STORE" ] && usage 1
[ $# -eq 0 ] && cat /dev/stdin > /dev/stdout && exit

wanted=($ARGS)

indices=
first=t
while read line; do
    OLD_IFS="$IFS"
    IFS="$DELIM"
    fields=($line)
    IFS="$OLD_IFS"

    if [ "$first" ]; then
        let "num_fields = ${#fields[@]} - 1"

        for want in ${wanted[@]}; do
            let "count = 0"
            for field in ${fields[@]}; do
                if [ "$field" == "$want" ]; then
                    echo -n "${want}#"
                    indices="$indices $count"
                    break
                fi
                let "count += 1"
            done
        done
        echo

        unset first
        continue
    fi

    for i in $indices; do
        if [ "$i" == "$num_fields" ]; then
            echo -n "${fields[@]:$i:${#fields[@]}}#"
        else
            echo -n "${fields[$i]}#"
        fi
    done
    echo
done </dev/stdin | column -s "#" -t