add a version subcommand

fix #63

Makefile

@@ -7,7 +7,7 @@ ip46tables: ip46tables.d/ip46tables.c
 	gcc -static ip46tables.d/ip46tables.c -o ip46tables
 
 reaction: app/* reaction.go go.mod go.sum
-	CGO_ENABLED=0 go build -buildvcs=false .
+	CGO_ENABLED=0 go build -buildvcs=false -ldflags "-X main.version=`git tag --sort=v:refname | tail -n1` -X main.commit=`git rev-parse --short HEAD`"
 
 reaction.deb: reaction ip46tables
 	chmod +x reaction ip46tables

app/main.go

@@ -72,7 +72,11 @@ func basicUsage() {
 		bold  = "\033[1m"
 		reset = "\033[0m"
 	)
-	fmt.Print(bold + `reaction start` + reset + `
+	fmt.Print(
+		bold + `reaction help` + reset + `
+  # print this help message
+
+` + bold + `reaction start` + reset + `
   # start the daemon
 
   # options:
@@ -106,6 +110,9 @@ func basicUsage() {
 ` + bold + `reaction test-regex` + reset + ` REGEX LINE       # test REGEX against LINE
 cat FILE | ` + bold + `reaction test-regex` + reset + ` REGEX # test REGEX against each line of FILE
 
+` + bold + `reaction version` + reset + `
+  # print version information
+
 see usage examples, service configurations and good practices
 on the ` + bold + `wiki` + reset + `: https://framagit.org/ppom/reaction-wiki
 `)
@@ -114,7 +121,7 @@ on the ` + bold + `wiki` + reset + `: https://framagit.org/ppom/reaction-wiki
 //go:embed example.yml
 var exampleConf string
 
-func Main() {
+func Main(version, commit string) {
 	if len(os.Args) <= 1 {
 		logger.Fatalln("No argument provided. Try `reaction help`")
 		basicUsage()
@@ -125,6 +132,9 @@ func Main() {
 	case "help", "-h", "-help", "--help":
 		basicUsage()
 
+	case "version", "-v", "--version":
+		fmt.Printf("reaction version %v commit %v\n", commit, version)
+
 	case "example-conf":
 		subCommandParse(f, 0)
 		fmt.Print(exampleConf)

reaction.go

@@ -5,5 +5,12 @@ import (
 )
 
 func main() {
-	app.Main()
+	app.Main(version, commit)
 }
+
+var (
+	// Must be passed when building
+	// go build -ldflags "-X app.commit XXX -X app.version XXX"
+	version string
+	commit  string
+)