bashrc-zone

#!/bin/bash

zone_add() {
    (
        [[ -z "$(tail -c 1 "$HOME/.bashrc")" ]] || echo # detect final new line
        echo "# START-ZONE $1"
        echo
        cat
        echo
        echo "# END-ZONE"
    ) >> "$HOME/.bashrc"
}

zone_remove() {
    [ -f "$HOME/.bashrc" ] && sed -i.bak "/^# START-ZONE $1$/,/^# END-ZONE$/d" "$HOME/.bashrc" || true
}

zone_check() {
    if [ ! -f "$HOME/.bashrc" ] || sed -n "/^# START-ZONE $1$/q" "$HOME/.bashrc"; then false; else true; fi
}

if [ "$1" == "add" ]; then
    zone_check "$2" && exit 1
    zone_add "$2"
elif [ "$1" == "remove" ]; then
    zone_remove "$2"
elif [ "$1" == "check" ]; then
    zone_check "$2"
else
    echo "usage: ${0##*/} add/remove/check <zone-name>"
fi