Add version info to binaries

main.go

@@ -7,6 +7,7 @@ import (
 	"path/filepath"
 )
 
+var version = flag.Bool("version", false, "print version information and exit")
 var list = flag.Bool("list", false, "list mode")
 var host = flag.String("host", "", "host mode")
 
@@ -14,6 +15,11 @@ func main() {
 	flag.Parse()
 	file := flag.Arg(0)
 
+	if *version == true {
+		fmt.Printf("%s version %d\n", os.Args[0], versionInfo())
+		return
+	}
+
 	if file == "" {
 		fmt.Printf("Usage: %s [options] path\n", os.Args[0])
 		os.Exit(1)

version.go

@@ -0,0 +1,15 @@
+package main
+
+// Deliberately uninitialized. See below.
+var build_version string
+
+// versionInfo returns a string containing the version information of the
+// current build. It's empty by default, but can be included as part of the
+// build process by setting the main.build_version variable.
+func versionInfo() string {
+	if build_version != "" {
+		return build_version
+	} else {
+		return "unknown"
+	}
+}

version_test.go

@@ -0,0 +1,13 @@
+package main
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestVersionInfo(t *testing.T) {
+	assert.Equal(t, "unknown", versionInfo())
+
+	build_version = "vXYZ"
+	assert.Equal(t, "vXYZ", versionInfo())
+}