dotnet-install.sh

#!/usr/bin/env bash
# Copyright (c) .NET Foundation and contributors. All rights reserved.
# Licensed under the MIT license. See LICENSE file in the project root for full license information.
#

# Stop script on NZEC
set -e
# Stop script if unbound variable found (use ${var:-} if intentional)
set -u
# By default cmd1 | cmd2 returns exit code of cmd2 regardless of cmd1 success
# This is causing it to fail
set -o pipefail

# Use in the the functions: eval $invocation
invocation='say_verbose "Calling: ${yellow:-}${FUNCNAME[0]} ${green:-}$*${normal:-}"'

# standard output may be used as a return value in the functions
# we need a way to write text on the screen in the functions so that
# it won't interfere with the return value.
# Exposing stream 3 as a pipe to standard output of the script itself
exec 3>&1

# Setup some colors to use. These need to work in fairly limited shells, like the Ubuntu Docker container where there are only 8 colors.
# See if stdout is a terminal
if [ -t 1 ] && command -v tput > /dev/null; then
    # see if it supports colors
    ncolors=$(tput colors || echo 0)
    if [ -n "$ncolors" ] && [ $ncolors -ge 8 ]; then
        bold="$(tput bold       || echo)"
        normal="$(tput sgr0     || echo)"
        black="$(tput setaf 0   || echo)"
        red="$(tput setaf 1     || echo)"
        green="$(tput setaf 2   || echo)"
        yellow="$(tput setaf 3  || echo)"
        blue="$(tput setaf 4    || echo)"
        magenta="$(tput setaf 5 || echo)"
        cyan="$(tput setaf 6    || echo)"
        white="$(tput setaf 7   || echo)"
    fi
fi

say_warning() {
    printf "%b\n" "${yellow:-}dotnet_install: Warning: $1${normal:-}" >&3
}

say_err() {
    printf "%b\n" "${red:-}dotnet_install: Error: $1${normal:-}" >&2
}

say() {
    # using stream 3 (defined in the beginning) to not interfere with stdout of functions
    # which may be used as return value
    printf "%b\n" "${cyan:-}dotnet-install:${normal:-} $1" >&3
}

say_verbose() {
    if [ "$verbose" = true ]; then
        say "$1"
    fi
}

# This platform list is finite - if the SDK/Runtime has supported Linux distribution-specific assets,
#   then and only then should the Linux distribution appear in this list.
# Adding a Linux distribution to this list does not imply distribution-specific support.
get_legacy_os_name_from_platform() {
    eval $invocation

    platform="$1"
    case "$platform" in
        "centos.7")
            echo "centos"
            return 0
            ;;
        "debian.8")
            echo "debian"
            return 0
            ;;
        "debian.9")
            echo "debian.9"
            return 0
            ;;
        "fedora.23")
            echo "fedora.23"
            return 0
            ;;
        "fedora.24")
            echo "fedora.24"
            return 0
            ;;
        "fedora.27")
            echo "fedora.27"
            return 0
            ;;
        "fedora.28")
            echo "fedora.28"
            return 0
            ;;
        "opensuse.13.2")
            echo "opensuse.13.2"
            return 0
            ;;
        "opensuse.42.1")
            echo "opensuse.42.1"
            return 0
            ;;
        "opensuse.42.3")
            echo "opensuse.42.3"
            return 0
            ;;
        "rhel.7"*)
            echo "rhel"
            return 0
            ;;
        "ubuntu.14.04")
            echo "ubuntu"
            return 0
            ;;
        "ubuntu.16.04")
            echo "ubuntu.16.04"
            return 0
            ;;
        "ubuntu.16.10")
            echo "ubuntu.16.10"
            return 0
            ;;
        "ubuntu.18.04")
            echo "ubuntu.18.04"
            return 0
            ;;
        "alpine.3.4.3")
            echo "alpine"
            return 0
            ;;
    esac
    return 1
}

get_legacy_os_name() {
    eval $invocation

    local uname=$(uname)
    if [ "$uname" = "Darwin" ]; then
        echo "osx"
        return 0
    elif [ -n "$runtime_id" ]; then
        echo $(get_legacy_os_name_from_platform "${runtime_id%-*}" || echo "${runtime_id%-*}")
        return 0
    else
        if [ -e /etc/os-release ]; then
            . /etc/os-release
            os=$(get_legacy_os_name_from_platform "$ID${VERSION_ID:+.${VERSION_ID}}" || echo "")
            if [ -n "$os" ]; then
                echo "$os"
                return 0
            fi
        fi
    fi

    say_verbose "Distribution specific OS name and version could not be detected: UName = $uname"
    return 1
}

get_linux_platform_name() {
    eval $invocation

    if [ -n "$runtime_id" ]; then
        echo "${runtime_id%-*}"
        return 0
    else
        if [ -e /etc/os-release ]; then
            . /etc/os-release
            echo "$ID${VERSION_ID:+.${VERSION_ID}}"
            return 0
        elif [ -e /etc/redhat-release ]; then
            local redhatRelease=$(</etc/redhat-release)
            if [[ $redhatRelease == "CentOS release 6."* || $redhatRelease == "Red Hat Enterprise Linux "*" release 6."* ]]; then
                echo "rhel.6"
                return 0
            fi
        fi
    fi

    say_verbose "Linux specific platform name and version could not be detected: UName = $uname"
    return 1
}

is_musl_based_distro() {
    (ldd --version 2>&1 || true) | grep -q musl
}

get_current_os_name() {
    eval $invocation

    local uname=$(uname)
    if [ "$uname" = "Darwin" ]; then
        echo "osx"
        return 0
    elif [ "$uname" = "FreeBSD" ]; then
        echo "freebsd"
        return 0
    elif [ "$uname" = "Linux" ]; then
        local linux_platform_name=""
        linux_platform_name="$(get_linux_platform_name)" || true

        if [ "$linux_platform_name" = "rhel.6" ]; then
            echo $linux_platform_name
            return 0
        elif is_musl_based_distro; then
            echo "linux-musl"
            return 0
        elif [ "$linux_platform_name" = "linux-musl" ]; then
            echo "linux-musl"
            return 0
        else
            echo "linux"
            return 0
        fi
    fi

    say_err "OS name could not be detected: UName = $uname"
    return 1
}

machine_has() {
    eval $invocation

    command -v "$1" > /dev/null 2>&1
    return $?
}

check_min_reqs() {
    local hasMinimum=false
    if machine_has "curl"; then
        hasMinimum=true
    elif machine_has "wget"; then
        hasMinimum=true
    fi

    if [ "$hasMinimum" = "false" ]; then
        say_err "curl (recommended) or wget are required to download dotnet. Install missing prerequisite to proceed."
        return 1
    fi
    return 0
}

# args:
# input - $1
to_lowercase() {
    #eval $invocation

    echo "$1" | tr '[:upper:]' '[:lower:]'
    return 0
}

# args:
# input - $1
remove_trailing_slash() {
    #eval $invocation

    local input="${1:-}"
    echo "${input%/}"
    return 0
}

# args:
# input - $1
remove_beginning_slash() {
    #eval $invocation

    local input="${1:-}"
    echo "${input#/}"
    return 0
}

# args:
# root_path - $1
# child_path - $2 - this parameter can be empty
combine_paths() {
    eval $invocation

    # TODO: Consider making it work with any number of paths. For now:
    if [ ! -z "${3:-}" ]; then
        say_err "combine_paths: Function takes two parameters."
        return 1
    fi

    local root_path="$(remove_trailing_slash "$1")"
    local child_path="$(remove_beginning_slash "${2:-}")"
    say_verbose "combine_paths: root_path=$root_path"
    say_verbose "combine_paths: child_path=$child_path"
    echo "$root_path/$child_path"
    return 0
}

get_machine_architecture() {
    eval $invocation

    if command -v uname > /dev/null; then
        CPUName=$(uname -m)
        case $CPUName in
        armv*l)
            echo "arm"
            return 0
            ;;
        aarch64|arm64)
            echo "arm64"
            return 0
            ;;
        esac
    fi

    # Always default to 'x64'
    echo "x64"
    return 0
}

# args:
# architecture - $1
get_normalized_architecture_from_architecture() {
    eval $invocation

    local architecture="$(to_lowercase "$1")"

    if [[ $architecture == \<auto\> ]]; then
        echo "$(get_machine_architecture)"
        return 0
    fi

    case "$architecture" in
        amd64|x64)
            echo "x64"
            return 0
            ;;
        arm)
            echo "arm"
            return 0
            ;;
        arm64)
            echo "arm64"
            return 0
            ;;
    esac

    say_err "Architecture \`$architecture\` not supported. If you think this is a bug, report it at https://github.com/dotnet/install-scripts/issues"
    return 1
}

# args:
# user_defined_os - $1
get_normalized_os() {
    eval $invocation

    local osname="$(to_lowercase "$1")"
    if [ ! -z "$osname" ]; then
        case "$osname" in
            osx | freebsd | rhel.6 | linux-musl | linux)
                echo "$osname"
                return 0
                ;;
            *)
                say_err "'$user_defined_os' is not a supported value for --os option, supported values are: osx, linux, linux-musl, freebsd, rhel.6. If you think this is a bug, report it at https://github.com/dotnet/install-scripts/issues."
                return 1
                ;;
        esac
    else
        osname="$(get_current_os_name)" || return 1
    fi
    echo "$osname"
    return 0
}

# args:
# quality - $1
get_normalized_quality() {
    eval $invocation

    local quality="$(to_lowercase "$1")"
    if [ ! -z "$quality" ]; then
        case "$quality" in
            daily | signed | validated | preview)
                echo "$quality"
                return 0
                ;;
            ga)
                #ga quality is available without specifying quality, so normalizing it to empty
                return 0
                ;;
            *)
                say_err "'$quality' is not a supported value for --quality option. Supported values are: daily, signed, validated, preview, ga. If you think this is a bug, report it at https://github.com/dotnet/install-scripts/issues."
                return 1
                ;;
        esac
    fi
    return 0
}

# args:
# channel - $1
get_normalized_channel() {
    eval $invocation

    local channel="$(to_lowercase "$1")"

    if [[ $channel == release/* ]]; then
        say_warning 'Using branch name with -Channel option is no longer supported with newer releases. Use -Quality option with a channel in X.Y format instead.';
    fi

    if [ ! -z "$channel" ]; then
        case "$channel" in
            lts)
                echo "LTS"
                return 0
                ;;
            *)
                echo "$channel"
                return 0
                ;;
        esac
    fi

    return 0
}

# args:
# runtime - $1
get_normalized_product() {
    eval $invocation

    local product=""
    local runtime="$(to_lowercase "$1")"
    if [[ "$runtime" == "dotnet" ]]; then
        product="dotnet-runtime"
    elif [[ "$runtime" == "aspnetcore" ]]; then
        product="aspnetcore-runtime"
    elif [ -z "$runtime" ]; then
        product="dotnet-sdk"
    fi
    echo "$product"
    return 0
}

# The version text returned from the feeds is a 1-line or 2-line string:
# For the SDK and the dotnet runtime (2 lines):
# Line 1: # commit_hash
# Line 2: # 4-part version
# For the aspnetcore runtime (1 line):
# Line 1: # 4-part version

# args:
# version_text - stdin
get_version_from_latestversion_file_content() {
    eval $invocation

    cat | tail -n 1 | sed 's/\r$//'
    return 0
}

# args:
# install_root - $1
# relative_path_to_package - $2
# specific_version - $3
is_dotnet_package_installed() {
    eval $invocation

    local install_root="$1"
    local relative_path_to_package="$2"
    local specific_version="${3//[$'\t\r\n']}"

    local dotnet_package_path="$(combine_paths "$(combine_paths "$install_root" "$relative_path_to_package")" "$specific_version")"
    say_verbose "is_dotnet_package_installed: dotnet_package_path=$dotnet_package_path"

    if [ -d "$dotnet_package_path" ]; then
        return 0
    else
        return 1
    fi
}

# args:
# azure_feed - $1
# channel - $2
# normalized_architecture - $3
get_version_from_latestversion_file() {
    eval $invocation

    local azure_feed="$1"
    local channel="$2"
    local normalized_architecture="$3"

    local version_file_url=null
    if [[ "$runtime" == "dotnet" ]]; then
        version_file_url="$azure_feed/Runtime/$channel/latest.version"
    elif [[ "$runtime" == "aspnetcore" ]]; then
        version_file_url="$azure_feed/aspnetcore/Runtime/$channel/latest.version"
    elif [ -z "$runtime" ]; then
         version_file_url="$azure_feed/Sdk/$channel/latest.version"
    else
        say_err "Invalid value for \$runtime"
        return 1
    fi
    say_verbose "get_version_from_latestversion_file: latest url: $version_file_url"

    download "$version_file_url" || return $?
    return 0
}

# args:
# json_file - $1
parse_globaljson_file_for_version() {
    eval $invocation

    local json_file="$1"
    if [ ! -f "$json_file" ]; then
        say_err "Unable to find \`$json_file\`"
        return 1
    fi

    sdk_section=$(cat $json_file | awk '/"sdk"/,/}/')
    if [ -z "$sdk_section" ]; then
        say_err "Unable to parse the SDK node in \`$json_file\`"
        return 1
    fi

    sdk_list=$(echo $sdk_section | awk -F"[{}]" '{print $2}')
    sdk_list=${sdk_list//[\" ]/}
    sdk_list=${sdk_list//,/$'\n'}

    local version_info=""
    while read -r line; do
      IFS=:
      while read -r key value; do
        if [[ "$key" == "version" ]]; then
          version_info=$value
        fi
      done <<< "$line"
    done <<< "$sdk_list"
    if [ -z "$version_info" ]; then
        say_err "Unable to find the SDK:version node in \`$json_file\`"
        return 1
    fi

    unset IFS;
    echo "$version_info"
    return 0
}

# args:
# azure_feed - $1
# channel - $2
# normalized_architecture - $3
# version - $4
# json_file - $5
get_specific_version_from_version() {
    eval $invocation

    local azure_feed="$1"
    local channel="$2"
    local normalized_architecture="$3"
    local version="$(to_lowercase "$4")"
    local json_file="$5"

    if [ -z "$json_file" ]; then
        if [[ "$version" == "latest" ]]; then
            local version_info
            version_info="$(get_version_from_latestversion_file "$azure_feed" "$channel" "$normalized_architecture" false)" || return 1
            say_verbose "get_specific_version_from_version: version_info=$version_info"
            echo "$version_info" | get_version_from_latestversion_file_content
            return 0
        else
            echo "$version"
            return 0
        fi
    else
        local version_info
        version_info="$(parse_globaljson_file_for_version "$json_file")" || return 1
        echo "$version_info"
        return 0
    fi
}

# args:
# azure_feed - $1
# channel - $2
# normalized_architecture - $3
# specific_version - $4
# normalized_os - $5
construct_download_link() {
    eval $invocation

    local azure_feed="$1"
    local channel="$2"
    local normalized_architecture="$3"
    local specific_version="${4//[$'\t\r\n']}"
    local specific_product_version="$(get_specific_product_version "$1" "$4")"
    local osname="$5"

    local download_link=null
    if [[ "$runtime" == "dotnet" ]]; then
        download_link="$azure_feed/Runtime/$specific_version/dotnet-runtime-$specific_product_version-$osname-$normalized_architecture.tar.gz"
    elif [[ "$runtime" == "aspnetcore" ]]; then
        download_link="$azure_feed/aspnetcore/Runtime/$specific_version/aspnetcore-runtime-$specific_product_version-$osname-$normalized_architecture.tar.gz"
    elif [ -z "$runtime" ]; then
        download_link="$azure_feed/Sdk/$specific_version/dotnet-sdk-$specific_product_version-$osname-$normalized_architecture.tar.gz"
    else
        return 1
    fi

    echo "$download_link"
    return 0
}

# args:
# azure_feed - $1
# specific_version - $2
# download link - $3 (optional)
get_specific_product_version() {
    # If we find a 'productVersion.txt' at the root of any folder, we'll use its contents
    # to resolve the version of what's in the folder, superseding the specified version.
    # if 'productVersion.txt' is missing but download link is already available, product version will be taken from download link
    eval $invocation

    local azure_feed="$1"
    local specific_version="${2//[$'\t\r\n']}"
    local package_download_link=""
    if [ $# -gt 2  ]; then
        local package_download_link="$3"
    fi
    local specific_product_version=null

    # Try to get the version number, using the productVersion.txt file located next to the installer file.
    local download_links=($(get_specific_product_version_url "$azure_feed" "$specific_version" true "$package_download_link")
        $(get_specific_product_version_url "$azure_feed" "$specific_version" false "$package_download_link"))

    for download_link in "${download_links[@]}"
    do
        say_verbose "Checking for the existence of $download_link"

        if machine_has "curl"
        then
            if ! specific_product_version=$(curl -s --fail "${download_link}${feed_credential}" 2>&1); then
                continue
            else
                echo "${specific_product_version//[$'\t\r\n']}"
                return 0
            fi

        elif machine_has "wget"
        then
            specific_product_version=$(wget -qO- "${download_link}${feed_credential}" 2>&1)
            if [ $? = 0 ]; then
                echo "${specific_product_version//[$'\t\r\n']}"
                return 0
            fi
        fi
    done
    
    # Getting the version number with productVersion.txt has failed. Try parsing the download link for a version number.
    say_verbose "Failed to get the version using productVersion.txt file. Download link will be parsed instead."
    specific_product_version="$(get_product_specific_version_from_download_link "$package_download_link" "$specific_version")"
    echo "${specific_product_version//[$'\t\r\n']}"
    return 0
}

# args:
# azure_feed - $1
# specific_version - $2
# is_flattened - $3
# download link - $4 (optional)
get_specific_product_version_url() {
    eval $invocation

    local azure_feed="$1"
    local specific_version="$2"
    local is_flattened="$3"
    local package_download_link=""
    if [ $# -gt 3  ]; then
        local package_download_link="$4"
    fi

    local pvFileName="productVersion.txt"
    if [ "$is_flattened" = true ]; then
        if [ -z "$runtime" ]; then
            pvFileName="sdk-productVersion.txt"
        elif [[ "$runtime" == "dotnet" ]]; then
            pvFileName="runtime-productVersion.txt"
        else
            pvFileName="$runtime-productVersion.txt"
        fi
    fi

    local download_link=null

    if [ -z "$package_download_link" ]; then
        if [[ "$runtime" == "dotnet" ]]; then
            download_link="$azure_feed/Runtime/$specific_version/${pvFileName}"
        elif [[ "$runtime" == "aspnetcore" ]]; then
            download_link="$azure_feed/aspnetcore/Runtime/$specific_version/${pvFileName}"
        elif [ -z "$runtime" ]; then
            download_link="$azure_feed/Sdk/$specific_version/${pvFileName}"
        else
            return 1
        fi
    else
        download_link="${package_download_link%/*}/${pvFileName}"
    fi

    say_verbose "Constructed productVersion link: $download_link"
    echo "$download_link"
    return 0
}

# args:
# download link - $1
# specific version - $2
get_product_specific_version_from_download_link()
{
    eval $invocation

    local download_link="$1"
    local specific_version="$2"
    local specific_product_version="" 

    if [ -z "$download_link" ]; then
        echo "$specific_version"
        return 0
    fi

    #get filename
    filename="${download_link##*/}"

    #product specific version follows the product name
    #for filename 'dotnet-sdk-3.1.404-linux-x64.tar.gz': the product version is 3.1.404
    IFS='-'
    read -ra filename_elems <<< "$filename"
    count=${#filename_elems[@]}
    if [[ "$count" -gt 2 ]]; then
        specific_product_version="${filename_elems[2]}"
    else
        specific_product_version=$specific_version
    fi
    unset IFS;
    echo "$specific_product_version"
    return 0
}

# args:
# azure_feed - $1
# channel - $2
# normalized_architecture - $3
# specific_version - $4
construct_legacy_download_link() {
    eval $invocation

    local azure_feed="$1"
    local channel="$2"
    local normalized_architecture="$3"
    local specific_version="${4//[$'\t\r\n']}"

    local distro_specific_osname
    distro_specific_osname="$(get_legacy_os_name)" || return 1

    local legacy_download_link=null
    if [[ "$runtime" == "dotnet" ]]; then
        legacy_download_link="$azure_feed/Runtime/$specific_version/dotnet-$distro_specific_osname-$normalized_architecture.$specific_version.tar.gz"
    elif [ -z "$runtime" ]; then
        legacy_download_link="$azure_feed/Sdk/$specific_version/dotnet-dev-$distro_specific_osname-$normalized_architecture.$specific_version.tar.gz"
    else
        return 1
    fi

    echo "$legacy_download_link"
    return 0
}

get_user_install_path() {
    eval $invocation

    if [ ! -z "${DOTNET_INSTALL_DIR:-}" ]; then
        echo "$DOTNET_INSTALL_DIR"
    else
        echo "$HOME/.dotnet"
    fi
    return 0
}

# args:
# install_dir - $1
resolve_installation_path() {
    eval $invocation

    local install_dir=$1
    if [ "$install_dir" = "<auto>" ]; then
        local user_install_path="$(get_user_install_path)"
        say_verbose "resolve_installation_path: user_install_path=$user_install_path"
        echo "$user_install_path"
        return 0
    fi

    echo "$install_dir"
    return 0
}

# args:
# relative_or_absolute_path - $1
get_absolute_path() {
    eval $invocation

    local relative_or_absolute_path=$1
    echo "$(cd "$(dirname "$1")" && pwd -P)/$(basename "$1")"
    return 0
}

# args:
# input_files - stdin
# root_path - $1
# out_path - $2
# override - $3
copy_files_or_dirs_from_list() {
    eval $invocation

    local root_path="$(remove_trailing_slash "$1")"
    local out_path="$(remove_trailing_slash "$2")"
    local override="$3"
    local osname="$(get_current_os_name)"
    local override_switch=$(
        if [ "$override" = false ]; then
            if [ "$osname" = "linux-musl" ]; then
                printf -- "-u";
            else
                printf -- "-n";
            fi
        fi)

    cat | uniq | while read -r file_path; do
        local path="$(remove_beginning_slash "${file_path#$root_path}")"
        local target="$out_path/$path"
        if [ "$override" = true ] || (! ([ -d "$target" ] || [ -e "$target" ])); then
            mkdir -p "$out_path/$(dirname "$path")"
            if [ -d "$target" ]; then
                rm -rf "$target"
            fi
            cp -R $override_switch "$root_path/$path" "$target"
        fi
    done
}

# args:
# zip_path - $1
# out_path - $2
extract_dotnet_package() {
    eval $invocation

    local zip_path="$1"
    local out_path="$2"

    local temp_out_path="$(mktemp -d "$temporary_file_template")"

    local failed=false
    tar -xzf "$zip_path" -C "$temp_out_path" > /dev/null || failed=true

    local folders_with_version_regex='^.*/[0-9]+\.[0-9]+[^/]+/'
    find "$temp_out_path" -type f | grep -Eo "$folders_with_version_regex" | sort | copy_files_or_dirs_from_list "$temp_out_path" "$out_path" false
    find "$temp_out_path" -type f | grep -Ev "$folders_with_version_regex" | copy_files_or_dirs_from_list "$temp_out_path" "$out_path" "$override_non_versioned_files"

    rm -rf "$temp_out_path"
    rm -f "$zip_path" && say_verbose "Temporary zip file $zip_path was removed"

    if [ "$failed" = true ]; then
        say_err "Extraction failed"
        return 1
    fi
    return 0
}

# args:
# remote_path - $1
# disable_feed_credential - $2
get_http_header()
{
    eval $invocation
    local remote_path="$1"
    local disable_feed_credential="$2"

    local failed=false
    local response
    if machine_has "curl"; then
        get_http_header_curl $remote_path $disable_feed_credential || failed=true
    elif machine_has "wget"; then
        get_http_header_wget $remote_path $disable_feed_credential || failed=true
    else
        failed=true
    fi
    if [ "$failed" = true ]; then
        say_verbose "Failed to get HTTP header: '$remote_path'."
        return 1
    fi
    return 0
}

# args:
# remote_path - $1
# disable_feed_credential - $2
get_http_header_curl() {
    eval $invocation
    local remote_path="$1"
    local disable_feed_credential="$2"

    remote_path_with_credential="$remote_path"
    if [ "$disable_feed_credential" = false ]; then
        remote_path_with_credential+="$feed_credential"
    fi

    curl_options="-I -sSL --retry 5 --retry-delay 2 --connect-timeout 15 "
    curl $curl_options "$remote_path_with_credential" 2>&1 || return 1
    return 0
}

# args:
# remote_path - $1
# disable_feed_credential - $2
get_http_header_wget() {
    eval $invocation
    local remote_path="$1"
    local disable_feed_credential="$2"
    local wget_options="-q -S --spider --tries 5 "

    local wget_options_extra=''

    # Test for options that aren't supported on all wget implementations.
    if [[ $(wget -h 2>&1 | grep -E 'waitretry|connect-timeout') ]]; then
        wget_options_extra="--waitretry 2 --connect-timeout 15 "
    else
        say "wget extra options are unavailable for this environment"
    fi

    remote_path_with_credential="$remote_path"
    if [ "$disable_feed_credential" = false ]; then
        remote_path_with_credential+="$feed_credential"
    fi

    wget $wget_options $wget_options_extra "$remote_path_with_credential" 2>&1

    return $?
}

# args:
# remote_path - $1
# [out_path] - $2 - stdout if not provided
download() {
    eval $invocation

    local remote_path="$1"
    local out_path="${2:-}"

    if [[ "$remote_path" != "http"* ]]; then
        cp "$remote_path" "$out_path"
        return $?
    fi

    local failed=false
    local attempts=0
    while [ $attempts -lt 3 ]; do
        attempts=$((attempts+1))
        failed=false
        if machine_has "curl"; then
            downloadcurl "$remote_path" "$out_path" || failed=true
        elif machine_has "wget"; then
            downloadwget "$remote_path" "$out_path" || failed=true
        else
            say_err "Missing dependency: neither curl nor wget was found."
            exit 1
        fi

        if [ "$failed" = false ] || [ $attempts -ge 3 ] || { [ ! -z $http_code ] && [ $http_code = "404" ]; }; then
            break
        fi

        say "Download attempt #$attempts has failed: $http_code $download_error_msg"
        say "Attempt #$((attempts+1)) will start in $((attempts*10)) seconds."
        sleep $((attempts*10))
    done



    if [ "$failed" = true ]; then
        say_verbose "Download failed: $remote_path"
        return 1
    fi
    return 0
}

# Updates global variables $http_code and $download_error_msg
downloadcurl() {
    eval $invocation
    unset http_code
    unset download_error_msg
    local remote_path="$1"
    local out_path="${2:-}"
    # Append feed_credential as late as possible before calling curl to avoid logging feed_credential
    # Avoid passing URI with credentials to functions: note, most of them echoing parameters of invocation in verbose output.
    local remote_path_with_credential="${remote_path}${feed_credential}"
    local curl_options="--retry 20 --retry-delay 2 --connect-timeout 15 -sSL -f --create-dirs "
    local curl_exit_code=0;
    if [ -z "$out_path" ]; then
        curl $curl_options "$remote_path_with_credential" 2>&1
        curl_exit_code=$?
    else
        curl $curl_options -o "$out_path" "$remote_path_with_credential" 2>&1
        curl_exit_code=$?
    fi
    
    if [ $curl_exit_code -gt 0 ]; then
        download_error_msg="Unable to download $remote_path."
        # Check for curl timeout codes
        if [[ $curl_exit_code == 7 || $curl_exit_code == 28 ]]; then
            download_error_msg+=" Failed to reach the server: connection timeout."
        else
            local disable_feed_credential=false
            local response=$(get_http_header_curl $remote_path $disable_feed_credential)
            http_code=$( echo "$response" | awk '/^HTTP/{print $2}' | tail -1 )
            if  [[ ! -z $http_code && $http_code != 2* ]]; then
                download_error_msg+=" Returned HTTP status code: $http_code."
            fi
        fi
        say_verbose "$download_error_msg"
        return 1
    fi
    return 0
}


# Updates global variables $http_code and $download_error_msg
downloadwget() {
    eval $invocation
    unset http_code
    unset download_error_msg
    local remote_path="$1"
    local out_path="${2:-}"
    # Append feed_credential as late as possible before calling wget to avoid logging feed_credential
    local remote_path_with_credential="${remote_path}${feed_credential}"
    local wget_options="--tries 20 "

    local wget_options_extra=''
    local wget_result=''

    # Test for options that aren't supported on all wget implementations.
    if [[ $(wget -h 2>&1 | grep -E 'waitretry|connect-timeout') ]]; then
        wget_options_extra="--waitretry 2 --connect-timeout 15 "
    else
        say "wget extra options are unavailable for this environment"
    fi

    if [ -z "$out_path" ]; then
        wget -q $wget_options $wget_options_extra -O - "$remote_path_with_credential" 2>&1
        wget_result=$?
    else
        wget $wget_options $wget_options_extra -O "$out_path" "$remote_path_with_credential" 2>&1
        wget_result=$?
    fi

    if [[ $wget_result != 0 ]]; then
        local disable_feed_credential=false
        local response=$(get_http_header_wget $remote_path $disable_feed_credential)
        http_code=$( echo "$response" | awk '/^  HTTP/{print $2}' | tail -1 )
        download_error_msg="Unable to download $remote_path."
        if  [[ ! -z $http_code && $http_code != 2* ]]; then
            download_error_msg+=" Returned HTTP status code: $http_code."
        # wget exit code 4 stands for network-issue
        elif [[ $wget_result == 4 ]]; then
            download_error_msg+=" Failed to reach the server: connection timeout."
        fi
        say_verbose "$download_error_msg"
        return 1
    fi

    return 0
}

get_download_link_from_aka_ms() {
    eval $invocation

    #quality is not supported for LTS or current channel
    if [[ ! -z "$normalized_quality"  && ("$normalized_channel" == "LTS" || "$normalized_channel" == "current") ]]; then
        normalized_quality=""
        say_warning "Specifying quality for current or LTS channel is not supported, the quality will be ignored."
    fi

    say_verbose "Retrieving primary payload URL from aka.ms for channel: '$normalized_channel', quality: '$normalized_quality', product: '$normalized_product', os: '$normalized_os', architecture: '$normalized_architecture'." 

    #construct aka.ms link
    aka_ms_link="https://aka.ms/dotnet"
    if  [ "$internal" = true ]; then
        aka_ms_link="$aka_ms_link/internal"
    fi
    aka_ms_link="$aka_ms_link/$normalized_channel"
    if [[ ! -z "$normalized_quality" ]]; then
        aka_ms_link="$aka_ms_link/$normalized_quality"
    fi
    aka_ms_link="$aka_ms_link/$normalized_product-$normalized_os-$normalized_architecture.tar.gz"
    say_verbose "Constructed aka.ms link: '$aka_ms_link'."

    #get HTTP response
    #do not pass credentials as a part of the $aka_ms_link and do not apply credentials in the get_http_header function
    #otherwise the redirect link would have credentials as well
    #it would result in applying credentials twice to the resulting link and thus breaking it, and in echoing credentials to the output as a part of redirect link
    disable_feed_credential=true
    response="$(get_http_header $aka_ms_link $disable_feed_credential)"

    say_verbose "Received response: $response"
    # Get results of all the redirects.
    http_codes=$( echo "$response" | awk '$1 ~ /^HTTP/ {print $2}' )
    # They all need to be 301, otherwise some links are broken (except for the last, which is not a redirect but 200 or 404).
    broken_redirects=$( echo "$http_codes" | sed '$d' | grep -v '301' )

    # All HTTP codes are 301 (Moved Permanently), the redirect link exists.
    if [[ -z "$broken_redirects" ]]; then
        aka_ms_download_link=$( echo "$response" | awk '$1 ~ /^Location/{print $2}' | tail -1 | tr -d '\r')

        if [[ -z "$aka_ms_download_link" ]]; then
            say_verbose "The aka.ms link '$aka_ms_link' is not valid: failed to get redirect location."
            return 1
        fi

        say_verbose "The redirect location retrieved: '$aka_ms_download_link'."
        return 0
    else
        say_verbose "The aka.ms link '$aka_ms_link' is not valid: received HTTP code: $(echo "$broken_redirects" | paste -sd "," -)."
        return 1
    fi
}

get_feeds_to_use()
{
    feeds=(
    "https://dotnetcli.azureedge.net/dotnet"
    "https://dotnetbuilds.azureedge.net/public"
    )

    if [[ -n "$azure_feed" ]]; then
        feeds=("$azure_feed")
    fi

    if [[ "$no_cdn" == "true" ]]; then
        feeds=(
        "https://dotnetcli.blob.core.windows.net/dotnet"
        "https://dotnetbuilds.blob.core.windows.net/public"
        )

        if [[ -n "$uncached_feed" ]]; then
            feeds=("$uncached_feed")
        fi
    fi
}

# THIS FUNCTION MAY EXIT (if the determined version is already installed).
generate_download_links() {

    download_links=()
    specific_versions=()
    effective_versions=()
    link_types=()

    # If generate_akams_links returns false, no fallback to old links. Just terminate.
    # This function may also 'exit' (if the determined version is already installed).
    generate_akams_links || return

    # Check other feeds only if we haven't been able to find an aka.ms link.
    if [[ "${#download_links[@]}" -lt 1 ]]; then
        for feed in ${feeds[@]}
        do
            # generate_regular_links may also 'exit' (if the determined version is already installed).
            generate_regular_links $feed || return
        done
    fi

    if [[ "${#download_links[@]}" -eq 0 ]]; then
        say_err "Failed to resolve the exact version number."
        return 1
    fi

    say_verbose "Generated ${#download_links[@]} links."
    for link_index in ${!download_links[@]}
    do
        say_verbose "Link $link_index: ${link_types[$link_index]}, ${effective_versions[$link_index]}, ${download_links[$link_index]}"
    done
}

# THIS FUNCTION MAY EXIT (if the determined version is already installed).
generate_akams_links() {
    local valid_aka_ms_link=true;

    normalized_version="$(to_lowercase "$version")"
    if [[ "$normalized_version" != "latest" ]] && [ -n "$normalized_quality" ]; then
        say_err "Quality and Version options are not allowed to be specified simultaneously. See https://docs.microsoft.com/en-us/dotnet/core/tools/dotnet-install-script#options for details."
        return 1
    fi

    if [[ -n "$json_file" || "$normalized_version" != "latest" ]]; then
        # aka.ms links are not needed when exact version is specified via command or json file
        return
    fi

    get_download_link_from_aka_ms || valid_aka_ms_link=false

    if [[ "$valid_aka_ms_link" == true ]]; then
        say_verbose "Retrieved primary payload URL from aka.ms link: '$aka_ms_download_link'."
        say_verbose "Downloading using legacy url will not be attempted."

        download_link=$aka_ms_download_link

        #get version from the path
        IFS='/'
        read -ra pathElems <<< "$download_link"
        count=${#pathElems[@]}
        specific_version="${pathElems[count-2]}"
        unset IFS;
        say_verbose "Version: '$specific_version'."

        #Retrieve effective version
        effective_version="$(get_specific_product_version "$azure_feed" "$specific_version" "$download_link")"

        # Add link info to arrays
        download_links+=($download_link)
        specific_versions+=($specific_version)
        effective_versions+=($effective_version)
        link_types+=("aka.ms")

        #  Check if the SDK version is already installed.
        if [[ "$dry_run" != true ]] && is_dotnet_package_installed "$install_root" "$asset_relative_path" "$effective_version"; then
            say "$asset_name with version '$effective_version' is already installed."
            exit 0
        fi

        return 0
    fi

    # if quality is specified - exit with error - there is no fallback approach
    if [ ! -z "$normalized_quality" ]; then
        say_err "Failed to locate the latest version in the channel '$normalized_channel' with '$normalized_quality' quality for '$normalized_product', os: '$normalized_os', architecture: '$normalized_architecture'."
        say_err "Refer to: https://aka.ms/dotnet-os-lifecycle for information on .NET Core support."
        return 1
    fi
    say_verbose "Falling back to latest.version file approach."
}

# THIS FUNCTION MAY EXIT (if the determined version is already installed)
# args:
# feed - $1
generate_regular_links() {
    local feed="$1"
    local valid_legacy_download_link=true

    specific_version=$(get_specific_version_from_version "$feed" "$channel" "$normalized_architecture" "$version" "$json_file") || specific_version='0'

    if [[ "$specific_version" == '0' ]]; then
        say_verbose "Failed to resolve the specific version number using feed '$feed'"
        return
    fi

    effective_version="$(get_specific_product_version "$feed" "$specific_version")"
    say_verbose "specific_version=$specific_version"

    download_link="$(construct_download_link "$feed" "$channel" "$normalized_architecture" "$specific_version" "$normalized_os")"
    say_verbose "Constructed primary named payload URL: $download_link"

    # Add link info to arrays
    download_links+=($download_link)
    specific_versions+=($specific_version)
    effective_versions+=($effective_version)
    link_types+=("primary")

    legacy_download_link="$(construct_legacy_download_link "$feed" "$channel" "$normalized_architecture" "$specific_version")" || valid_legacy_download_link=false

    if [ "$valid_legacy_download_link" = true ]; then
        say_verbose "Constructed legacy named payload URL: $legacy_download_link"
    
        download_links+=($legacy_download_link)
        specific_versions+=($specific_version)
        effective_versions+=($effective_version)
        link_types+=("legacy")
    else
        legacy_download_link=""
        say_verbose "Cound not construct a legacy_download_link; omitting..."
    fi

    #  Check if the SDK version is already installed.
    if [[ "$dry_run" != true ]] && is_dotnet_package_installed "$install_root" "$asset_relative_path" "$effective_version"; then
        say "$asset_name with version '$effective_version' is already installed."
        exit 0
    fi
}

print_dry_run() {

    say "Payload URLs:"

    for link_index in "${!download_links[@]}"
        do
            say "URL #$link_index - ${link_types[$link_index]}: ${download_links[$link_index]}"
    done

    resolved_version=${specific_versions[0]}
    repeatable_command="./$script_name --version "\""$resolved_version"\"" --install-dir "\""$install_root"\"" --architecture "\""$normalized_architecture"\"" --os "\""$normalized_os"\"""
    
    if [ ! -z "$normalized_quality" ]; then
        repeatable_command+=" --quality "\""$normalized_quality"\"""
    fi

    if [[ "$runtime" == "dotnet" ]]; then
        repeatable_command+=" --runtime "\""dotnet"\"""
    elif [[ "$runtime" == "aspnetcore" ]]; then
        repeatable_command+=" --runtime "\""aspnetcore"\"""
    fi

    repeatable_command+="$non_dynamic_parameters"

    if [ -n "$feed_credential" ]; then
        repeatable_command+=" --feed-credential "\""<feed_credential>"\"""
    fi

    say "Repeatable invocation: $repeatable_command"
}

calculate_vars() {
    eval $invocation

    script_name=$(basename "$0")
    normalized_architecture="$(get_normalized_architecture_from_architecture "$architecture")"
    say_verbose "Normalized architecture: '$normalized_architecture'."
    normalized_os="$(get_normalized_os "$user_defined_os")"
    say_verbose "Normalized OS: '$normalized_os'."
    normalized_quality="$(get_normalized_quality "$quality")"
    say_verbose "Normalized quality: '$normalized_quality'."
    normalized_channel="$(get_normalized_channel "$channel")"
    say_verbose "Normalized channel: '$normalized_channel'."
    normalized_product="$(get_normalized_product "$runtime")"
    say_verbose "Normalized product: '$normalized_product'."
    install_root="$(resolve_installation_path "$install_dir")"
    say_verbose "InstallRoot: '$install_root'."

    if [[ "$runtime" == "dotnet" ]]; then
        asset_relative_path="shared/Microsoft.NETCore.App"
        asset_name=".NET Core Runtime"
    elif [[ "$runtime" == "aspnetcore" ]]; then
        asset_relative_path="shared/Microsoft.AspNetCore.App"
        asset_name="ASP.NET Core Runtime"
    elif [ -z "$runtime" ]; then
        asset_relative_path="sdk"
        asset_name=".NET Core SDK"
    fi

    get_feeds_to_use
}

install_dotnet() {
    eval $invocation
    local download_failed=false
    local download_completed=false

    mkdir -p "$install_root"
    zip_path="$(mktemp "$temporary_file_template")"
    say_verbose "Zip path: $zip_path"

    for link_index in "${!download_links[@]}"
    do
        download_link="${download_links[$link_index]}"
        specific_version="${specific_versions[$link_index]}"
        effective_version="${effective_versions[$link_index]}"
        link_type="${link_types[$link_index]}"

        say "Attempting to download using $link_type link $download_link"

        # The download function will set variables $http_code and $download_error_msg in case of failure.
        download_failed=false
        download "$download_link" "$zip_path" 2>&1 || download_failed=true

        if [ "$download_failed" = true ]; then
            case $http_code in
            404)
                say "The resource at $link_type link '$download_link' is not available."
                ;;
            *)
                say "Failed to download $link_type link '$download_link': $download_error_msg"
                ;;
            esac
            rm -f "$zip_path" 2>&1 && say_verbose "Temporary zip file $zip_path was removed"
        else
            download_completed=true
            break
        fi
    done

    if [[ "$download_completed" == false ]]; then
        say_err "Could not find \`$asset_name\` with version = $specific_version"
        say_err "Refer to: https://aka.ms/dotnet-os-lifecycle for information on .NET Core support"
        return 1
    fi

    say "Extracting zip from $download_link"
    extract_dotnet_package "$zip_path" "$install_root" || return 1

    #  Check if the SDK version is installed; if not, fail the installation.
    # if the version contains "RTM" or "servicing"; check if a 'release-type' SDK version is installed.
    if [[ $specific_version == *"rtm"* || $specific_version == *"servicing"* ]]; then
        IFS='-'
        read -ra verArr <<< "$specific_version"
        release_version="${verArr[0]}"
        unset IFS;
        say_verbose "Checking installation: version = $release_version"
        if is_dotnet_package_installed "$install_root" "$asset_relative_path" "$release_version"; then
            say "Installed version is $effective_version"
            return 0
        fi
    fi

    #  Check if the standard SDK version is installed.
    say_verbose "Checking installation: version = $effective_version"
    if is_dotnet_package_installed "$install_root" "$asset_relative_path" "$effective_version"; then
        say "Installed version is $effective_version"
        return 0
    fi

    # Version verification failed. More likely something is wrong either with the downloaded content or with the verification algorithm.
    say_err "Failed to verify the version of installed \`$asset_name\`.\nInstallation source: $download_link.\nInstallation location: $install_root.\nReport the bug at https://github.com/dotnet/install-scripts/issues."
    say_err "\`$asset_name\` with version = $effective_version failed to install with an error."
    return 1
}

args=("$@")

local_version_file_relative_path="/.version"
bin_folder_relative_path=""
temporary_file_template="${TMPDIR:-/tmp}/dotnet.XXXXXXXXX"

channel="LTS"
version="Latest"
json_file=""
install_dir="<auto>"
architecture="<auto>"
dry_run=false
no_path=false
no_cdn=false
azure_feed=""
uncached_feed=""
feed_credential=""
verbose=false
runtime=""
runtime_id=""
quality=""
internal=false
override_non_versioned_files=true
non_dynamic_parameters=""
user_defined_os=""

while [ $# -ne 0 ]
do
    name="$1"
    case "$name" in
        -c|--channel|-[Cc]hannel)
            shift
            channel="$1"
            ;;
        -v|--version|-[Vv]ersion)
            shift
            version="$1"
            ;;
        -q|--quality|-[Qq]uality)
            shift
            quality="$1"
            ;;
        --internal|-[Ii]nternal)
            internal=true
            non_dynamic_parameters+=" $name"
            ;;
        -i|--install-dir|-[Ii]nstall[Dd]ir)
            shift
            install_dir="$1"
            ;;
        --arch|--architecture|-[Aa]rch|-[Aa]rchitecture)
            shift
            architecture="$1"
            ;;
        --os|-[Oo][SS])
            shift
            user_defined_os="$1"
            ;;
        --shared-runtime|-[Ss]hared[Rr]untime)
            say_warning "The --shared-runtime flag is obsolete and may be removed in a future version of this script. The recommended usage is to specify '--runtime dotnet'."
            if [ -z "$runtime" ]; then
                runtime="dotnet"
            fi
            ;;
        --runtime|-[Rr]untime)
            shift
            runtime="$1"
            if [[ "$runtime" != "dotnet" ]] && [[ "$runtime" != "aspnetcore" ]]; then
                say_err "Unsupported value for --runtime: '$1'. Valid values are 'dotnet' and 'aspnetcore'."
                if [[ "$runtime" == "windowsdesktop" ]]; then
                    say_err "WindowsDesktop archives are manufactured for Windows platforms only."
                fi
                exit 1
            fi
            ;;
        --dry-run|-[Dd]ry[Rr]un)
            dry_run=true
            ;;
        --no-path|-[Nn]o[Pp]ath)
            no_path=true
            non_dynamic_parameters+=" $name"
            ;;
        --verbose|-[Vv]erbose)
            verbose=true
            non_dynamic_parameters+=" $name"
            ;;
        --no-cdn|-[Nn]o[Cc]dn)
            no_cdn=true
            non_dynamic_parameters+=" $name"
            ;;
        --azure-feed|-[Aa]zure[Ff]eed)
            shift
            azure_feed="$1"
            non_dynamic_parameters+=" $name "\""$1"\"""
            ;;
        --uncached-feed|-[Uu]ncached[Ff]eed)
            shift
            uncached_feed="$1"
            non_dynamic_parameters+=" $name "\""$1"\"""
            ;;
        --feed-credential|-[Ff]eed[Cc]redential)
            shift
            feed_credential="$1"
            #feed_credential should start with "?", for it to be added to the end of the link.
            #adding "?" at the beginning of the feed_credential if needed.
            [[ -z "$(echo $feed_credential)" ]] || [[ $feed_credential == \?* ]] || feed_credential="?$feed_credential"
            ;;
        --runtime-id|-[Rr]untime[Ii]d)
            shift
            runtime_id="$1"
            non_dynamic_parameters+=" $name "\""$1"\"""
            say_warning "Use of --runtime-id is obsolete and should be limited to the versions below 2.1. To override architecture, use --architecture option instead. To override OS, use --os option instead."
            ;;
        --jsonfile|-[Jj][Ss]on[Ff]ile)
            shift
            json_file="$1"
            ;;
        --skip-non-versioned-files|-[Ss]kip[Nn]on[Vv]ersioned[Ff]iles)
            override_non_versioned_files=false
            non_dynamic_parameters+=" $name"
            ;;
        -?|--?|-h|--help|-[Hh]elp)
            script_name="$(basename "$0")"
            echo ".NET Tools Installer"
            echo "Usage: $script_name [-c|--channel <CHANNEL>] [-v|--version <VERSION>] [-p|--prefix <DESTINATION>]"
            echo "       $script_name -h|-?|--help"
            echo ""
            echo "$script_name is a simple command line interface for obtaining dotnet cli."
            echo ""
            echo "Options:"
            echo "  -c,--channel <CHANNEL>         Download from the channel specified, Defaults to \`$channel\`."
            echo "      -Channel"
            echo "          Possible values:"
            echo "          - Current - most current release"
            echo "          - LTS - most current supported release"
            echo "          - 2-part version in a format A.B - represents a specific release"
            echo "              examples: 2.0; 1.0"
            echo "          - 3-part version in a format A.B.Cxx - represents a specific SDK release"
            echo "              examples: 5.0.1xx, 5.0.2xx."
            echo "              Supported since 5.0 release"
            echo "          Note: The version parameter overrides the channel parameter when any version other than 'latest' is used."
            echo "  -v,--version <VERSION>         Use specific VERSION, Defaults to \`$version\`."
            echo "      -Version"
            echo "          Possible values:"
            echo "          - latest - the latest build on specific channel"
            echo "          - 3-part version in a format A.B.C - represents specific version of build"
            echo "              examples: 2.0.0-preview2-006120; 1.1.0"
            echo "  -q,--quality <quality>         Download the latest build of specified quality in the channel."
            echo "      -Quality"
            echo "          The possible values are: daily, signed, validated, preview, GA."
            echo "          Works only in combination with channel. Not applicable for current and LTS channels and will be ignored if those channels are used." 
            echo "          For SDK use channel in A.B.Cxx format. Using quality for SDK together with channel in A.B format is not supported." 
            echo "          Supported since 5.0 release." 
            echo "          Note: The version parameter overrides the channel parameter when any version other than 'latest' is used, and therefore overrides the quality."
            echo "  --internal,-Internal               Download internal builds. Requires providing credentials via --feed-credential parameter."
            echo "  --feed-credential <FEEDCREDENTIAL> Token to access Azure feed. Used as a query string to append to the Azure feed."
            echo "      -FeedCredential                This parameter typically is not specified."
            echo "  -i,--install-dir <DIR>             Install under specified location (see Install Location below)"
            echo "      -InstallDir"
            echo "  --architecture <ARCHITECTURE>      Architecture of dotnet binaries to be installed, Defaults to \`$architecture\`."
            echo "      --arch,-Architecture,-Arch"
            echo "          Possible values: x64, arm, and arm64"
            echo "  --os <system>                    Specifies operating system to be used when selecting the installer."
            echo "          Overrides the OS determination approach used by the script. Supported values: osx, linux, linux-musl, freebsd, rhel.6."
            echo "          In case any other value is provided, the platform will be determined by the script based on machine configuration."
            echo "          Not supported for legacy links. Use --runtime-id to specify platform for legacy links."
            echo "          Refer to: https://aka.ms/dotnet-os-lifecycle for more information."
            echo "  --runtime <RUNTIME>                Installs a shared runtime only, without the SDK."
            echo "      -Runtime"
            echo "          Possible values:"
            echo "          - dotnet     - the Microsoft.NETCore.App shared runtime"
            echo "          - aspnetcore - the Microsoft.AspNetCore.App shared runtime"
            echo "  --dry-run,-DryRun                  Do not perform installation. Display download link."
            echo "  --no-path, -NoPath                 Do not set PATH for the current process."
            echo "  --verbose,-Verbose                 Display diagnostics information."
            echo "  --azure-feed,-AzureFeed            For internal use only."
            echo "                                     Allows using a different storage to download SDK archives from."
            echo "                                     This parameter is only used if --no-cdn is false."
            echo "  --uncached-feed,-UncachedFeed      For internal use only."
            echo "                                     Allows using a different storage to download SDK archives from."
            echo "                                     This parameter is only used if --no-cdn is true."
            echo "  --skip-non-versioned-files         Skips non-versioned files if they already exist, such as the dotnet executable."
            echo "      -SkipNonVersionedFiles"
            echo "  --no-cdn,-NoCdn                    Disable downloading from the Azure CDN, and use the uncached feed directly."
            echo "  --jsonfile <JSONFILE>              Determines the SDK version from a user specified global.json file."
            echo "                                     Note: global.json must have a value for 'SDK:Version'"
            echo "  -?,--?,-h,--help,-Help             Shows this help message"
            echo ""
            echo "Install Location:"
            echo "  Location is chosen in following order:"
            echo "    - --install-dir option"
            echo "    - Environmental variable DOTNET_INSTALL_DIR"
            echo "    - $HOME/.dotnet"
            exit 0
            ;;
        *)
            say_err "Unknown argument \`$name\`"
            exit 1
            ;;
    esac

    shift
done

say "Note that the intended use of this script is for Continuous Integration (CI) scenarios, where:"
say "- The SDK needs to be installed without user interaction and without admin rights."
say "- The SDK installation doesn't need to persist across multiple CI runs."
say "To set up a development environment or to run apps, use installers rather than this script. Visit https://dotnet.microsoft.com/download to get the installer.\n"

if [ "$internal" = true ] && [ -z "$(echo $feed_credential)" ]; then
    message="Provide credentials via --feed-credential parameter."
    if [ "$dry_run" = true ]; then
        say_warning "$message"
    else
        say_err "$message"
        exit 1
    fi
fi

check_min_reqs
calculate_vars
# generate_regular_links call below will 'exit' if the determined version is already installed.
generate_download_links

if [[ "$dry_run" = true ]]; then
    print_dry_run
    exit 0
fi

install_dotnet

bin_path="$(get_absolute_path "$(combine_paths "$install_root" "$bin_folder_relative_path")")"
if [ "$no_path" = false ]; then
    say "Adding to current process PATH: \`$bin_path\`. Note: This change will be visible only when sourcing script."
    export PATH="$bin_path":"$PATH"
else
    say "Binaries of dotnet can be found in $bin_path"
fi

say "Note that the script does not resolve dependencies during installation."
say "To check the list of dependencies, go to https://docs.microsoft.com/dotnet/core/install, select your operating system and check the \"Dependencies\" section."
say "Installation finished successfully."