Merge pull request #35 from ramil600/version-command

added --version flag:

Makefile

@@ -15,5 +15,6 @@ test:
 fmt:
 	gofmt -w -l -s $(SRCS)
 
-gofail: $(SRCS)
-	go build -v
+gofail: 
+	GO_BUILD_FLAGS="-v" ./build.sh
+	./gofail --version

build.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+
+GIT_SHA=$(git rev-parse --short HEAD || echo "GitNotFound")
+
+# Set GO_LDFLAGS="-s" for building without symbols for debugging.
+GO_LDFLAGS=("-X 'main.GitSHA=${GIT_SHA}'")
+go build $GO_BUILD_FLAGS -ldflags="$GO_LDFLAGS" -o gofail

gofail.go

@@ -22,11 +22,29 @@ import (
 	"os"
 	"path"
 	"path/filepath"
+	"runtime"
 	"strings"
 
 	"go.etcd.io/gofail/code"
 )
 
+var (
+	// Git SHA Value will be set during build
+	GitSHA = "Not provided (use ./build.sh instead of go build)"
+
+	Version = "0.1.0"
+)
+
+var usageLine = `Usage:
+gofail enable [list of files or directories]
+    Enable the failpoints
+
+gofail disable [list of files or directories]
+    Disable the checkpoints
+	
+gofail --version
+    Show the version of gofail`
+
 type xfrmFunc func(io.Writer, io.Reader) ([]*code.Failpoint, error)
 
 func xfrmFile(xfrm xfrmFunc, path string) ([]*code.Failpoint, error) {
@@ -152,7 +170,7 @@ func writeBinding(file string, fps []*code.Failpoint) {
 
 func main() {
 	if len(os.Args) < 2 {
-		fmt.Println("not enough arguments")
+		fmt.Println(usageLine)
 		os.Exit(1)
 	}
 
@@ -164,8 +182,14 @@ func main() {
 		enable = true
 	case "disable":
 		xfrm = code.ToComments
+	case "--version":
+		fmt.Println("Git SHA: ", GitSHA)
+		fmt.Println("Go Version: ", runtime.Version())
+		fmt.Println("gofail Version: ", Version)
+		fmt.Printf("Go OS/Arch: %s/%s\n", runtime.GOOS, runtime.GOARCH)
+		os.Exit(1)
 	default:
-		fmt.Println("expected enable or disable")
+		fmt.Println(usageLine)
 		os.Exit(1)
 	}