add README

README.md

@@ -0,0 +1,107 @@
+# GO Playground
+This repo ist to learn and play with GO.
+
+All Code is written and tested on a Ubuntu 20.4 Linux. 
+
+Learn more about [GO](https://go.dev/)
+
+## Install from Release
+```bash
+# Download release, change the number to latest release
+curl -OL https://golang.org/dl/go1.17.5.linux-amd64.tar.gz
+# verify integrity of download, compare with website's shown hash
+sha256sum go1.16.7.linux-amd64.tar.gz
+# extract tarball
+sudo tar -C /usr/local -xvf go1.17.5.linux-amd64.tar.gz
+# set up paths
+sudo nano ~/.profile
+>   export PATH=$PATH:/usr/local/go/bin
+source ~/.profile
+# confirm installation
+which go
+go version
+```
+
+## Install from Source
+```bash
+# install requirements
+sudo apt install git gcc 
+# get source repository
+git clone https://go.googlesource.com/go goroot
+cd goroot
+#  <tag> is the version string of the release
+git checkout <tag>
+cd src
+# install
+./all.bash
+# test installation
+which go
+go version
+```
+
+The compilation environment can be customized by environment variables (but not required). Heres a short list
+- `$GOROOT`: root of the GO tree, often `$HOME/go1.X`
+- `$GOPATH`: directory where Go projects outside the Go distribution are typically checked out. Executables outside the Go distribution are installed in $GOPATH/bin (or $GOBIN, if set)
+- `$GOBIN`: directory where executables outside the Go distribution are installed using the go command
+
+To change any variable, edit your `~/.profile` file. Scroll all the way down to the end of the file and add the following with your specifications (sample here shows default values)
+```bash
+GOROOT=$HOME/go1.X
+GOPATH=$HOME/go
+GOBIN=$GOPATH/bin
+```
+Feel free to change it to your needs. Finally make the system aware of the new profile and run `source ~/.profile`
+
+
+### Update your GO Version
+GO releases can be fetched with the installed repository above. To never forget any release you can join the [golang-announce mailing list](https://groups.google.com/group/golang-announce).
+
+To update to the latest release, simply run
+```bash
+cd go/src
+git fetch
+# change <tag> to latest release tag e.g. go1.9
+git checkout <tag>
+./all.bash
+```
+
+## First programm
+```go
+package main
+
+import "fmt"
+
+func main() {
+	fmt.Printf("hello, world\n")
+}
+```
+Build and run this program:
+```bash
+go run hello.go
+```
+
+## Code to binary
+The `go run` command is used as a shortcut for compiling and running a program that requires frequent changes. 
+
+When you’ve finished your code and want to run it without compiling each time, use `go build` to turn your code into an executable binary. Building code into an executable binary consolidates the application into a single file with all the (support) code necessary to execute the binary. 
+
+Once built, run `go install` to place the program on an executable file path to run it from anywhere on the system.
+
+To build and install executables you need an `go.mod` file with your executable definitions. Follow the [helloworld program](1-hello-world/hello.go) to see how.
+
+```bash
+# make sure to run from same directory as .go file
+go build
+# execute binary
+./hello
+# install to system
+go install
+# execute global binary
+hello
+```
+
+## Install additional tools
+Several Go tools are kept in the `golang.org/x/tools` repository. To install one of the tools, e.g. `gopls`:
+```bash
+go install golang.org/x/tools/gopls@latest
+```