Bash script to change golang version

golangInstalVersion

#!/bin/bash

if [ -z "$GOInstallDir" ] ; then
#echo ${BASH_SOURCE[0]}
	GOInstallDir="$(dirname "$(readlink -f "$0")")"
fi

if [[ "$1" =~ (^$|-h)  ]] ; then
	echo "Usage: $(basename "$0") [-h] <version>"
	echo "Example usage: $(basename "$0") 1.10"
	echo "This tool downloads and installs a user defined version of go"
	echo ""
	echo "$(basename "$0") will use GOInstallDir as its root for all files"
	echo "All go binary's will be placed in <GOInstallDir>/current/bin"
	echo "GOROOT should be set to <GOInstallDir>/current"
	echo ""
	echo "<GOInstallDir>/current is a symlink to <GOInstallDir>/go<version>/go"
	echo "$(basename "$0") will not remove any old versions"
        echo "allowing for quick switching to another version."
	echo "The default value of GOInstallDir is the same folder as this"
	echo "script, note that symlinks are followed allowing this script"
	echo "allowing for links from path folders."
	echo ""
	echo "Current value of GOInstallDir: \"$GOInstallDir\""
	echo "GOInstallDir can be overridden using the env variable GOInstallDir"
	echo "example:"
	echo "cd /bin && ln -s /opt/golang/$(basename "$0")"
	echo "GOInstallDir's default value would be /opt/golang/"
	echo "GOInstallDir can be reconfigured the env var"
	echo "GOInstallDir=/tmp $(basename "$0")"
	echo ""
	echo "Processor arch is determined using uname -m"
	echo "arch can be set using the env var GOInstallArch"
	echo ""
	echo "OS is set to linux by default"
	echo "OS can be overridden using the env variable GOInstallOS"
	echo ""
	echo "Its the users responsibility to preform cleanup:"
	echo "It is safe to remove all <GOInstallDir>/[...].tar.gz"
	echo "It is safe to remove <GOInstallDir>/go<version>/go folders except for"
	echo "The currently used version"
	exit 0 
fi

echo "Switching to go version $1"

cd "$GOInstallDir"


#Arch
if [ -z "$goInstallArch" ] ; then
	GOInstallArch="$(uname -m)"
fi
GOInstallArch=$(echo "$GOInstallArch" | sed 's| ||g;s|x86[-_]64|amd64|I;s|ARMv8|arm64|I;s|^x86$|386|I;s|ARMv6|armv6l|I;s|\(.*\)|\L\1|g')



#OS
if [ -z "$GOInstallOS" ] ; then
	GOInstallOS="linux"
fi
GOInstallOS=$(echo "$GOInstallOS" | sed 's| ||g;s|\(.*\)|\L\1|g')


if ! [ -d "go$1" ] ; then
	tarbollName="go$1.$GOInstallOS-$GOInstallArch.tar.gz"
	if ! [ -f "$tarbollName" ] ; then
	echo "go version $1 not found downloading using the follwing go env:"
echo "version: $1"
echo "arch:    $GOInstallArch"
echo "os:      $GOInstallOS"
wget "https://golang.org/dl/$tarbollName" || (echo "Unable to download version! quiting"; exit 1)
fi

echo "Unpacking $tarbollName"
mkdir "go$1"
tar xf "$tarbollName" -C "./go$1" || (echo "Unpack failed quitting"; rm -r "go$1" ; exit 1 )

rm "$tarbollName"
fi

rm "current"
ln -s "go$1/go" "current"

echo "Golang verison $1 set"
echo ""

echo "Checking install..."


PathErr=0
Err=0
for f in $(ls "current/bin/") ; do

whichF="$(which "$f")"
pathF="$(readlink -f "$whichF")"
curentF="$(readlink -f "current/bin/$f")"
#echo "$pathF"
#echo "$curentF"
if [ "$pathF" != "$curentF" ]; then
	Err=1
	PathErr=1
	if ! [ -z "$pathF" ] ; then
		echo -e "WARNING: path appears to be misconfigured for \e[31m$f\e[0m"
		echo -e "- \e[31m$f\e[0m will call \e[31m$whichF\e[0m"
	else
		echo -e "WARNING: \e[31m$f\e[0m could not be found i PATH"
	fi
	echo ""
fi


done


if [ "$PathErr" -eq "0" ] ; then
	echo "OK: Binarys in $(pwd)/current/bin/ are all found in path"
fi

if [[ ":$PATH:" != *"$(pwd)/current/bin"* ]] ; then
	if [ "$PathErr" -eq "1" ]; then
		echo -e "Path related warings may be caused by the fact that \e[31m$(pwd)\e[0m is not in \$PATH variable"
		echo "If modifying path isnt an option consider adding symlinks to binarys in a path folerd:"
		echo "cd <folder_in_path> && ln -s \"$(pwd)/current/bin/<missing_binary>\""
	else
		echo "INFO: $(pwd)/current/bin is not in the path, all binarys seams to be linked to from path"
	fi
else
	echo "OK: $(pwd)/current/bin is in the users path."
		
fi

goenv=$(go env)

goVersionEnv=$(echo "$goenv" | sed '/^GOVERSION/!d;s|[A-Z="]||gI')
if [ "$goVersionEnv" != "$1" ]; then
	Err=1
	echo "WARNING: Version reported by go env in GOVERISON is $goVersion not $1"
else
	echo "OK: GOVERISON variable reported by go env is correct"
fi

goRootEnv=$(echo "$goenv" | sed '/^GOROOT/!d;s|GOROOT="||;s|"||')
goRootEnvLink=$(readlink -f "$goRootEnv")
if [ "$goRootEnvLink" != "$(readlink -f "current/")" ]; then
	Err=1
	echo "GOROOT reported by go env appears to be misconfigured"
	echo "GOROOT shoudl be: $(pwd)/current"
	echo "GOROOT is:        $goRootEnv"
	echo "Note this test may be buggy due to lack of testing...."
else
	echo "OK: the GOROOT variable reported by go env is correct" 
fi

goRootEnvLink=$(readlink -f "$goRootEnv")
if [ "$(readlink -f "$GOROOT")" != "$(readlink -f "current/")" ]; then
	Err=1
	echo "The envrioment varaible GOROOT appears to be misconfigured"
	echo "GOROOT shoudl be: $(pwd)/current"
	echo "GOROOT is:        $GOROOT"
	echo "Note this test may be buggy due to lack of testing...."
else
	echo "OK: GOROOT enviroment variable is correct"
fi


if [ "$Err" -eq "0" ] ; then
	echo "Install looks good"
fi