Golang/Install

Install on Ubuntu

Note: Update to reflect Ubuntu 20.04

Ubuntu 18.04, 20.04 inc. WSL, WSL2

# List available versions
apt-cache policy golang-1.1?
sudo apt install golang-go    # default version
sudo apt install golang-1.16  # specific

Official way of installing it Download from https://golang.org/dl/ and extract it into /usr/local, creating a Go tree in /usr/local/go

VERSION=1.17 # 1.16.7
curl -O https://storage.googleapis.com/golang/go${VERSION}.linux-amd64.tar.gz
sudo rm -rf /usr/local/go && sudo tar -C /usr/local -xzvf go${VERSION}.linux-amd64.tar.gz

Add /usr/local/go/bin to the PATH environment variable. You can do this by adding this line to your /etc/profile (for a system-wide installation) or $HOME/.profile:

# Official
export PATH=$PATH:/usr/local/go/bin

# Optional using alternatives
sudo update-alternatives --install "/usr/bin/go" "go" "/usr/local/go/bin/go" 2 #adds to the $PATH

# Set $GOPATH
export GOPATH=$HOME/go 
export PATH=$PATH:$GOPATH/bin

Multiple versions using alternatives

You can have multiple versions fo Golang installed in your system. The way to manage the current version in use is to use update-alternatives

Display best options

sudo update-alternatives --display go
go - auto mode
  link best version is /usr/local/go/bin/go
  link currently points to /usr/local/go/bin/go
  link go is /usr/bin/go
/usr/local/go/bin/go - priority 2

Before

Selection    Path                  Priority   Status
 ------------------------------------------------------------
   0            /usr/bin/golang-go     10        auto mode
   1            /usr/bin/gccgo-go      5         manual mode
   2            /usr/bin/golang-go     10        manual mode

Action: Installed manually unzipped GoLang into /usr/local/go but was not added to alternatives. Use command below to add it on:

sudo update-alternatives --install "/usr/bin/go" "go" "/usr/local/go/bin/go" 2

After

Selection    Path                  Priority   Status
 ------------------------------------------------------------
 * 0            /usr/bin/golang-go     10        auto mode
   1            /usr/bin/gccgo-go      5         manual mode
   2            /usr/bin/golang-go     10        manual mode
   3            /usr/local/go/bin/go   2         manual mode

Then run command to change go binary available in your shell

sudo update-alternatives --config go  #then select ''3''

When you run

$ go version #the version of ''go'' will be the one from <tt>/usr/local/go</tt> location.

Shell autocompletion

Features

• Complete go command, including sub commands and all flags.
• Complete packages names or .go files when necessary.
• Complete test names after -run flag.
• it can add any Go program autocomplete to your shell, check for details in the example.

Supported shells: bash, zsh, fish

Install

go get -u github.com/posener/complete/gocomplete 
gocomplete -install # Uninstall by gocomplete -uninstall

Troubleshooting

What is GOPATH?

• it's an environment variable with a list paths to look for Go code, on Unix it's colon-separated string
• usually GOPATH is $HOME/go where bin and src directories exists. Each time you execute go get -u <url>, the binaries will be placed in $HOME/go/bin and code in $HOME/go/src
• therefore $HOME/go/bin needs to be in the $PATH
• default go directory: /usr/local/go is called GOROOT
• default go bin directory: /usr/local/go/bin that needs to be in $PATH

Allow 'sudo go <subcommand>'

sudo visudo # then add to'secure_path' '.../go/bin' directory
Defaults secure_path=".../bin:/usr/local/go/bin"

Get go environment variables

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/home/ubuntu/.cache/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/ubuntu/go"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/go"
GOTMPDIR=""
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build629810470=/tmp/go-build -gno-record-gcc-switches"

References

• for loop dev.to

Tutorials

• GoLang by example contains for-range loop