Go (Golang) is installed on Windows via its msi installer available on Go's website. The latest version at the time of writing this article was 1.11.4 and the installer go1.11.4.windows-amd64.msi.
Installation is straightforward:
By default, installer creates or modifies the following environment variables:
In System space:
Variable (created): GOROOT
Value: C:\Go\
Description: Go installation location.
Variable (value appended): Path
Value: C:\Go\bin
Description: Go binaries location.
In User space:
Variable (created): GOPATH
Value: %USERPROFILE%\go
Description: User's go workspace path.
Variable (value appended): Path
Value: %USERPROFILE%\go\bin
Description: User's Go applications' binaries location.
Go workspace:
Upon installation, C:\Go\bin contains three binaries:
Let's see what are the command line arguments of go tool:
If we already have some Go project in some Git repository (like GitHub), we can use get command to clone the given repository:
Repository is cloned to C:\dev\go\src\github.com\BojanKomazec\go-hello-world directory.
Repository shall be written without starting https:// as go get would report an error:
This my repository only has .gitignore and README.md files so let's add some code. First, let's create a directory named hello and in it a go file with the following content:
C:\dev\go\src\github.com\BojanKomazec\go-hello-world\hello\hello.go:
Building this file with:
...creates a hello.exe file in the same directory and we can run it:
To install that build as a package, we have to run:
This deploys application binary in C:\dev\go\bin directory.
Let's now analyse code in the go source file above.
This line tells the Go compiler that the package should compile as an executable program. Its entry point will be function main(). If we were building a shared library, we would use package lib directive and there would not be main() function in the package.
import statement imports a package into other package. Here, we wanted to use function which prints a string onto standard output. Such function, Printf, is available in the fmt package which comes from the Go standard library. Go compiler looks for standard library packages on paths specified in GOROOT and your and third-party packages on path specified in GOPATH environment variables.
Understanding Golang Packages
Package “main” and func “main”
Installation is straightforward:
By default, installer creates or modifies the following environment variables:
In System space:
Variable (created): GOROOT
Value: C:\Go\
Description: Go installation location.
Variable (value appended): Path
Value: C:\Go\bin
Description: Go binaries location.
Variable (created): GOPATH
Value: %USERPROFILE%\go
Description: User's go workspace path.
Variable (value appended): Path
Value: %USERPROFILE%\go\bin
Description: User's Go applications' binaries location.
Go workspace:
- a directory with two subdirectories: bin and src
- src typically contains all repositories with Go projects
- bin contains built and then installed Go application binaries
- can be set at arbitrary location; I set mine to C:\dev\go (and also set User space Path to C:\dev\go\bin)
Upon installation, C:\Go\bin contains three binaries:
- go - Tool for managing Go source code
- godoc - Documentation tool; parses Go source code - including comments - and produces documentation as HTML or plain text
- gofmt - Go source code formatter; uses tabs for indentation and blanks for alignment.
Let's see what are the command line arguments of go tool:
>go
Go is a tool for managing Go source code.
Usage:
go <command> [arguments]
The commands are:
bug start a bug report
build compile packages and dependencies
clean remove object files and cached files
doc show documentation for package or symbol
env print Go environment information
fix update packages to use new APIs
fmt gofmt (reformat) package sources
generate generate Go files by processing source
get download and install packages and dependencies
install compile and install packages and dependencies
list list packages or modules
mod module maintenance
run compile and run Go program
test test packages
tool run specified go tool
version print Go version
vet report likely mistakes in packages
Use "go help <command>" for more information about a command.
Additional help topics:
buildmode build modes
c calling between Go and C
cache build and test caching
environment environment variables
filetype file types
go.mod the go.mod file
gopath GOPATH environment variable
gopath-get legacy GOPATH go get
goproxy module proxy protocol
importpath import path syntax
modules modules, module versions, and more
module-get module-aware go get
packages package lists and patterns
testflag testing flags
testfunc testing functions
If we already have some Go project in some Git repository (like GitHub), we can use get command to clone the given repository:
C:\dev\go\src>go get github.com/BojanKomazec/go-hello-world
package github.com/BojanKomazec/go-hello-world: no Go files in
C:\dev\go\src\github.com\BojanKomazec\go-hello-world
package github.com/BojanKomazec/go-hello-world: no Go files in
C:\dev\go\src\github.com\BojanKomazec\go-hello-world
Repository is cloned to C:\dev\go\src\github.com\BojanKomazec\go-hello-world directory.
Repository shall be written without starting https:// as go get would report an error:
C:\dev\go\src>go get https://github.com/BojanKomazec/go-hello-world
package https:/github.com/BojanKomazec/go-hello-world: https:/github.com/BojanKomazec/go-hello-world: invalid import path: malformed import path "https:/github.com/BojanKomazec/go-hello-world": invalid char ':'
package https:/github.com/BojanKomazec/go-hello-world: https:/github.com/BojanKomazec/go-hello-world: invalid import path: malformed import path "https:/github.com/BojanKomazec/go-hello-world": invalid char ':'
This my repository only has .gitignore and README.md files so let's add some code. First, let's create a directory named hello and in it a go file with the following content:
C:\dev\go\src\github.com\BojanKomazec\go-hello-world\hello\hello.go:
package main
import "fmt"
func main() {
fmt.Printf("hello, world\n")
}
Building this file with:
C:\dev\go\src\github.com\BojanKomazec\go-hello-world\hello>go build
...creates a hello.exe file in the same directory and we can run it:
C:\dev\go\src\github.com\BojanKomazec\go-hello-world\hello>hello
hello, world
hello, world
To install that build as a package, we have to run:
C:\dev\go\src\github.com\BojanKomazec\go-hello-world\hello>go install
This deploys application binary in C:\dev\go\bin directory.
go tool and Git
If we add, commit and then try to push hello.go file to remote repository, we'll be prompted by Git to enter our GitHub credentials as by default go get sets the https-based URL of the remote. We can verify that with:
We can set SSH-based URL by executing:
Let's verify it:
If we add, commit and then try to push hello.go file to remote repository, we'll be prompted by Git to enter our GitHub credentials as by default go get sets the https-based URL of the remote. We can verify that with:
C:\dev\go\src\github.com\BojanKomazec\go-hello-world>git remote show origin
* remote origin
Fetch URL: https://github.com/BojanKomazec/go-hello-world
Push URL: https://github.com/BojanKomazec/go-hello-world
HEAD branch: master
Remote branch:
master tracked
Local branch configured for 'git pull':
master merges with remote master
Local ref configured for 'git push':
master pushes to master (up to date)
* remote origin
Fetch URL: https://github.com/BojanKomazec/go-hello-world
Push URL: https://github.com/BojanKomazec/go-hello-world
HEAD branch: master
Remote branch:
master tracked
Local branch configured for 'git pull':
master merges with remote master
Local ref configured for 'git push':
master pushes to master (up to date)
We can set SSH-based URL by executing:
>git remote set-url origin git@github.com:BojanKomazec/go-hello-world.git
Let's verify it:
C:\dev\go\src\github.com\BojanKomazec\go-hello-world>git remote show origin
Enter passphrase for key '/c/Users/komazec/.ssh/id_rsa':
* remote origin
Fetch URL: git@github.com:BojanKomazec/go-hello-world.git
Push URL: git@github.com:BojanKomazec/go-hello-world.git
HEAD branch: master
Remote branch:
master tracked
Local branch configured for 'git pull':
master merges with remote master
Local ref configured for 'git push':
master pushes to master (up to date)
Enter passphrase for key '/c/Users/komazec/.ssh/id_rsa':
* remote origin
Fetch URL: git@github.com:BojanKomazec/go-hello-world.git
Push URL: git@github.com:BojanKomazec/go-hello-world.git
HEAD branch: master
Remote branch:
master tracked
Local branch configured for 'git pull':
master merges with remote master
Local ref configured for 'git push':
master pushes to master (up to date)
Let's now analyse code in the go source file above.
package main
func main() {
...
}
This line tells the Go compiler that the package should compile as an executable program. Its entry point will be function main(). If we were building a shared library, we would use package lib directive and there would not be main() function in the package.
import "fmt"
...
fmt.Printf("hello, world\n")
...
fmt.Printf("hello, world\n")
import statement imports a package into other package. Here, we wanted to use function which prints a string onto standard output. Such function, Printf, is available in the fmt package which comes from the Go standard library. Go compiler looks for standard library packages on paths specified in GOROOT and your and third-party packages on path specified in GOPATH environment variables.
Project on GutHub:
https://github.com/BojanKomazec/go-hello-worldReferences:
golang.org: Go installation on WindowsUnderstanding Golang Packages
Package “main” and func “main”
