Chapter 2. go

In Go Toolset, go is provided by the go-toolset-1.10-golang package and is automatically installed with the go-toolset-1.10 package. See Section 1.4, “Installing Go Toolset”.

When creating a Go program, developers must follow the rules for Go workspace layout. The .go source files must be placed in subdirectory of $GOPATH/src.

mkdir -p $GOPATH/src/hello
cd $GOPATH/src/hello
touch hello.go

$ mkdir -p $GOPATH/src/hello
$ cd $GOPATH/src/hello
$ touch hello.go

package main

import (
    "fmt"
    "net/http"
)

func Welcome(w http.ResponseWriter, req *http.Request) {

    fmt.Fprintf(w, "<h1>Welcome to the Go toolset.</h1>")

}

func main() {

    fmt.Println("Hello.")
    fmt.Println("Starting http server.")
    // Register handler function
    http.HandleFunc("/welcome", Welcome)
    fmt.Println("Go to localhost:8080/welcome")
    fmt.Println("To terminate press CTRL+C.")
    // Start server
    http.ListenAndServe(":8080", nil)

}

package main

import (
    "fmt"
    "net/http"
)

func Welcome(w http.ResponseWriter, req *http.Request) {

    fmt.Fprintf(w, "<h1>Welcome to the Go toolset.</h1>")

}

func main() {

    fmt.Println("Hello.")
    fmt.Println("Starting http server.")
    // Register handler function
    http.HandleFunc("/welcome", Welcome)
    fmt.Println("Go to localhost:8080/welcome")
    fmt.Println("To terminate press CTRL+C.")
    // Start server
    http.ListenAndServe(":8080", nil)

}

Additional Resources

To build a Go program using the command line, change to the project directory and run the go compiler as follows:

scl enable go-toolset-1.10 'go build -o output_file go_main_package'

$ scl enable go-toolset-1.10 'go build -o output_file go_main_package'

This creates a binary file named output_file in the current working directory. If the -o option is omitted, the compiler creates a file named after the go_main_package, go_main_package.

If go_main_package is not a main package or if multiple projects or *.go files are specified, the resulting binaries are discarded. In that case, the go build command is used to verify that the supplied projects or files can be built.

Note that you can execute any command using the scl utility, causing it to be run with the Go Toolset binaries available. This allows you to run a shell session with Go Toolset go directly available:

scl enable go-toolset-1.10 'bash'

$ scl enable go-toolset-1.10 'bash'

scl enable go-toolset-1.10 'go build hello.go'

$ scl enable go-toolset-1.10 'go build hello.go'

When go compiles a program, it creates an executable binary file. To run this program on the command line, change to the directory with the executable file and run the program:

./file_name

$ ./file_name

./hello

$ ./hello
Hello.
Starting http server.
Go to localhost:8080/welcome
To terminate press CTRL+C.

Installing a Go project means that its executable files and libraries are compiled, and copied to appropriate directories in the Go Workspace. The go tool can then use the executable files and libraries in further projects. Dependencies of the installed project are installed, too.

To install a Go project, run the go tool:

scl enable go-toolset-1.10 'go install go_project'

$ scl enable go-toolset-1.10 'go install go_project'

The install command accepts the same options as the build command.

To download a 3rd party Go project from an online source and install it, run the go tool:

scl enable go-toolset-1.10 'go get 3rd_party_go_project'

$ scl enable go-toolset-1.10 'go get 3rd_party_go_project'

For more details about the possible values of 3rd_party_go_project option, run the following command:

scl enable go-toolset-1.10 'go help importpath'

$ scl enable go-toolset-1.10 'go help importpath'

A detailed description of the go compiler and its features is beyond the scope of this book. For more information, see the resources listed below.

Installed Documentation

Online Documentation

See Also