Upgrade a Go installation to the latest version

getgo.sh

#!/usr/bin/env bash

# getgo helps you install any version of go, or simply upgrade
# to the latest.
#
# Go versions will be installed under "/usr/local/go/{VERSION}",
# and "/usr/local/go/latest" will always point to the latest
# version installed.
#
# Upgrade to the latest:
#   getgo
#
# Download a specific version:
#   getgo VERSION [CHECKSUM] [GOOS] [GOARCH]
#
# Requirements:
#   curl, jq
#
# (c) Mohamed Attahri – https://github.com/mohamedattahri

set -e

NUMBER=$1
CHECKSUM=$2

# Create destination dir
GODIR=/usr/local/go
if [ ! -d "$GODIR" ]
then
    sudo -v
    sudo mkdir -p ${GODIR}
    sudo chown `whoami` ${GODIR}
fi    

GOOS=$3
GOARCH=$4

if type "go" > /dev/null 2>&1
then
    GOOS=`go env GOOS`
    GOARCH=`go env GOARCH`
else
    if [ -z "${GOOS}" ]
    then
        read -p "GOOS:" GOOS
    fi
    if [ -z "${GOARCH}" ]
    then
        read -p "GOARCH:" GOARCH
    fi
fi    

# Retrieve the latest version number and checksum
if [ -z "$1" ]
then
    printf "Fetching latest version..."
    RAW=`curl -LsS "https://go.dev/dl/?mode=json"`
    NUMBER=`echo ${RAW} | jq '.[0].version' | tr -d \" | tr -d 'go'`
    CHECKSUM=`echo ${RAW} | jq ".[0].files[] | select(.filename | test(\"go${NUMBER}.${GOOS}-${GOARCH}.tar.gz\")).sha256" | tr -d \"`
    printf "(${NUMBER})\n"
fi
VERSION=${NUMBER}.${GOOS}-${GOARCH}
TMP=/tmp/go${VERSION}.tar.gz

# Check if already installed.
if type "go" > /dev/null 2>&1
then
    if echo "go version go${NUMBER} ${GOOS}/${GOARCH}" | grep -q "$(go version)"
    then
        echo "Go ${NUMBER} (${GOOS}/${GOARCH}) is already installed."
        exit 0
    fi
fi    

# Download if necessary
if [ ! -f ${TMP} ]
then
    printf "Downloading ${VERSION}.tar.gz..."
    curl -LsS "https://go.dev/dl/go${VERSION}.tar.gz" > ${TMP}
    printf "(`ls -lh ${TMP} | awk '{print $5}'`)\n"
fi

# Verify checksum
if [ ! -z "$CHECKSUM" ]
then
    printf "Verifying checksum..."
    echo "${CHECKSUM} *${TMP}" | shasum -a256 -c -s
    printf "(${CHECKSUM})\n"
fi

# Unpack
DEST=${GODIR}/${NUMBER}
printf "Unpacking..."
mkdir -p ${DEST}
tar -xf ${TMP} -C ${DEST} --strip-components=1
rm -f ${TMP}
printf "(${DEST})\n"
printf "Go ${NUMBER} (${GOOS}/${GOARCH}) installed.\n"

# Latest
LATEST=`find ${GODIR} -type d -maxdepth 1 | sort -V | tail -n1`
ln -snf `realpath ${LATEST}` ${GODIR}/latest

# Check Path
GOROOT=${GODIR}/latest/bin
if [[ :$PATH: != *:"${GOROOT}":* ]]
then
    echo "Add \"${GOROOT}" to \$PATH"
fi

exit 0