hello world project

1-hello-world/go.mod

@@ -0,0 +1,3 @@
+module example/user/hello
+
+go 1.17

1-hello-world/hello.go

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+package main
+
+import "fmt"
+
+func main() {
+	fmt.Printf("hello, world\n")
+}

1-hello-world/readme.md

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+# Hello World
+Steps to reproduce
+```bash
+mkdir 1-hello-world
+cd 1-hello-world
+go mod init example/user/hello
+cat go.mod
+# first statement in a Go source file must be package name. Executable commands must always use package main. 
+
+# to run
+go run hello.go
+
+# to build and run binary
+go build
+./hello
+
+# to install binary to system
+go install example/user/hello
+# or
+go install
+```