Script to Switch Between Active Versions of Go

goto.sh

#! /bin/bash

go_dir="/usr/local/go"
version=${1}
version_dir="#unset#"
dl_url="#unset#"
gos_dir="/usr/local/gos"
tar_file=".temp-go.tar.gz"
temp_dir=".temp"
arch=linux-amd64

function fatal_error() {
    printf "$(tput setaf 1)ERROR: $1$(tput sgr 0)\n"
    exit 1
}

function success_msg() {
    printf "$(tput setaf 2)$1$(tput setaf 7)\n\n"
}

function info_msg() {
    printf "$(tput setaf 4)$1$(tput setaf 7)\n"
}

function alert_msg() {
    printf "$(tput setaf 3)$1$(tput setaf 7)\n"
}

function init() {
    if [ ! -d "$gos_dir" ]; then
        info_msg "creating go version directory at $gos_dir"
        sudo mkdir $gos_dir
        sudo chmod 555 $gos_dir

        if [ $? -gt 0 ]; then
            fatal_error "unable to create required directory structure"
        fi
    fi
}

function read_required_version() {
    if [ -z $version ]; then
        alert_msg 'select a locally available version or specify one to download:'
        
        local_versions=(`ls -l $gos_dir | awk 'NR > 1 { print $9 }' | sed 's/go_//g' | sed 's/_/\./g'`)
        specify_opt="specify"

        select version in "${local_versions[@]}" "${specify_opt}"; do
            case $version in *) break;;
            esac
        done

        if [ "$version" = "${specify_opt}" ]; then
            read -p "enter version:" version
        fi

        if [ -z $version ]; then
            fatal_error "a valid version is required"
        fi

    fi

    version_dir="go_`echo $version | sed "s/\./_/g"`"
    dl_url="https://golang.org/dl/go$version.${arch}.tar.gz"
}

function get_required_version() {
    if [ ! -d "$gos_dir/$version_dir" ]; then
        info_msg "version $version of go not found locally. downloading from $dl_url ..."

        sudo rm -rf $tar_file $temp_dir 2> /dev/null
        sudo mkdir ./$temp_dir

        sudo wget -q -O $tar_file $dl_url 

        if [ "$?" -gt 0 ]; then
            fatal_error "error downloading version $version of go from $dl_url"
        fi

        info_msg "download successful. extracting version $version of go to $gos_dir/$version_dir ..."

        sudo tar -C $temp_dir -xzf $tar_file
        sudo mv $temp_dir/go $gos_dir/$version_dir
        sudo rm -rf $tar_file $temp_dir

        info_msg "extraction successful"
    fi
}

function activate_required_version() {
    sudo rm -rf $go_dir 2> /dev/null
    sudo ln -s $gos_dir/$version_dir $go_dir
}

init

read_required_version
alert_msg "activating version $version of go...."

get_required_version
info_msg "version $version of go available locally"

activate_required_version
success_msg "go version $version now active"

Summary

goto enables quick and stable switching of the currently active version of Go on a Linux or Mac system to any specified version.

It will download the specified version from the official Go repo and set it is as the active version on the host system. A local cache of previously downloaded versions is maintained allowing such versions to be activated and deactivated rapidly.

Usage

The below examples assume that goto is installed as per the instructions in the next section. Where that is not the case, replace goto with the name of the local script file, typically ./goto.sh

Activate a Specific Version (non-interactive)

The exact version required can be passed as an argument to the script:

goto 1.20.2

This form is particularly useful in scripts. For example, the below shows how to run Go commands against multiple versions of Go, one of which (1.19.7) was already available in the cache and one (1.20.2) which was not initially, but then subsequently is.

The Go command in question here is simply go version, but it illustrates the point:

$ goto 1.20.2
activating version 1.20.2 of go....
version 1.20.2of go not found locally. downloading from https://golang.org/dl/go1.20.2.linux-amd64.tar.gz ...
download successful. extracting version 1.20.2 of go to /usr/local/gos/go_1_20_2 ...
extraction successful
version 1.20.2 of go available locally
go version 1.20.2 now active

$ go version 
go version go1.20.2 linux/amd64

$ goto 1.19.7
activating version 1.19.7 of go....
version 1.19.7 of go available locally
go version 1.19.7 now active

$ go version 
go version go1.19.7 linux/amd64

$ goto 1.20.2
activating version 1.20.2 of go....
version 1.20.2 of go available locally
go version 1.20.2 now active

$ go version 
go version go1.20.2 linux/amd64

Select or Specify a Version

For ease of use, a version can be selected for activation from the cache, rather than entering it manually:

$ goto

This will return a list of cached versions, or an option to specify a specific one if it transpires the required version isn't actually in the cache. Example output is shown below:

select a locally available version or specify one to download:
1) 1.16.3
2) 1.17.1
3) 1.18.1
4) 1.19.4
5) 1.20.2
6) specify
#? 

Enter the number that corresponds to the required version if it is shown or, alternatively, enter the number that corresponds to specify and then enter the desired version number manually when prompted, as shown below.

$ enter version:
1.20.2

Once the version has been entered, or specified, it will be downloaded, if required, and activated. This will be confirmed with output similar to the below

activating version 1.20.2 of go....
version 1.20.2 of go available locally
go version 1.20.2 now active

Installation

goto can be kept as an adhoc script or installed for continued use. To install. run the below in the directory that the script exists

rm -rf goto.sh 2> /dev/null; \
wget "https://gist.githubusercontent.com/comradequinn/45b9eef8bde320b6e474f65061b84f78/raw/d1f3e8bea8d16751f3bd1f307258a3a575dfa335/goto.sh" && \
sudo cp goto.sh /usr/local/bin/goto && \
rm -f goto.sh && \
sudo chmod 555 /usr/local/bin/goto && \
echo "goto installed"

Mac users should then execute one of the below after the installation to adjust the target architecture as required:

sudo sed -i'.bak' "s/arch\=linux-amd64/arch\=darwin-arm64/g" /usr/local/bin/goto && rm -f /usr/local/bin/goto.bak 2> /dev/null # apple silicon 

sudo sed -i'.bak' "s/arch\=linux-amd64/arch\=darwin-amd64/g" /usr/local/bin/goto && rm -f /usr/local/bin/goto.bak 2> /dev/null # apple on intel