file_downloader.sh

file_downloader() {
    local url="" output=""
    local downloader=""
    
    # Parse arguments
    while [[ "$#" -gt 0 ]]; do
        case "$1" in
            --output=*)
                output="${1#--output=}"
                ;;
            --output)
                output="$2"
                shift
                ;;
            *)
                url="$1"
                ;;
        esac
        shift
    done
    
    if [[ -z "$url" ]]; then
        echo "Error: No URL provided." >&2
        return 1
    fi
    
    # Determine available downloader
    if command -v wget &>/dev/null; then
        downloader="wget"
    elif command -v curl &>/dev/null; then
        downloader="curl"
    elif command -v fetch &>/dev/null; then
        downloader="fetch"
    elif command -v aria2c &>/dev/null; then
        downloader="aria2c"
    elif command -v httpie &>/dev/null; then
        downloader="http"
    else
        echo "Error: No supported download utility found (wget, curl, fetch, aria2c, httpie)." >&2
        return 1
    fi
    
    # Download file based on the selected tool
    if [[ -n "$output" ]]; then
        case "$downloader" in
            wget)
                wget --output-document="$output" "$url"
                ;;
            curl)
                curl -o "$output" "$url"
                ;;
            fetch)
                fetch -o "$output" "$url"
                ;;
            aria2c)
                aria2c -o "$output" "$url"
                ;;
            http)
                http --download "$url" --output "$output"
                ;;
        esac
    else
        case "$downloader" in
            wget)
                wget "$url"
                ;;
            curl)
                curl -O "$url"
                ;;
            fetch)
                fetch "$url"
                ;;
            aria2c)
                aria2c "$url"
                ;;
            http)
                http --download "$url"
                ;;
        esac
    fi
}

usage_example.sh

usage_example() {
  # Absolute file location
  file_downloader http://raw.github.com/caiogondim/bullet-train-oh-my-zsh-theme/master/bullet-train.zsh-theme --output=$ZSH_CUSTOM/themes/bullet-train.zsh-theme

  # Relative file location
  file_downloader http://raw.github.com/caiogondim/bullet-train-oh-my-zsh-theme/master/bullet-train.zsh-theme --output=./themes/bullet-train.zsh-theme

  # No file location (download to current directory)
  file_downloader http://raw.github.com/caiogondim/bullet-train-oh-my-zsh-theme/master/bullet-train.zsh-theme
}