Where are package main and module fmt located?

Getting Help
1

Many go programs start with :

package main
import "fmt"

My GOPATH:

echo  $GOPATH
/home/debian/go

Where are package main and module fmt located?

2

This depends on where you installed golang, and it is in the src directory.

3

Try /usr/local/go/src/fmt/ for the fmt module.
The package main statement is saying that this file is part of a program. If it were a library it would be package <name of the library>