Add a --version flag for the root command

Makefile

@@ -1,11 +1,12 @@
 BIN := vct
+VERSION := $(shell git describe --tags --always --dirty)
 
 .PHONY: all $(BIN) clean
 
 all: $(BIN)
 
 $(BIN):
-	go build -ldflags='-s -w'
+	go build -ldflags='-s -w -X main.version=$(VERSION)'
 
 clean:
 	rm -f $(BIN)

cmd/root.go

@@ -8,22 +8,28 @@ import (
 	"github.com/spf13/cobra"
 )
 
-func showHelp(cmd *cobra.Command, args []string) {
-	cmd.Help()
-}
+var Version string
 
 func MakeCmd() *cobra.Command {
 	cmd := &cobra.Command{
 		Use:   "vct",
 		Short: "Vlab's Container Tool",
 		Long:  "Vlab's Container Tool, a versatile tool for managing containers on Proxmox VE",
 		Args:  cobra.NoArgs,
-		Run:   showHelp,
 	}
 	cmd.CompletionOptions.HiddenDefaultCmd = true
 	cmd.AddCommand(df.MakeCmd())
 	cmd.AddCommand(findpid.MakeCmd())
 	cmd.AddCommand(iostat.MakeCmd())
 	cmd.AddCommand(pressure.MakeCmd())
+	pVersion := cmd.Flags().BoolP("version", "v", false, "show version")
+
+	cmd.Run = func(cmd *cobra.Command, args []string) {
+		if *pVersion {
+			cmd.Println(cmd.Name(), Version)
+		} else {
+			cmd.Help()
+		}
+	}
 	return cmd
 }

main.go

@@ -6,7 +6,10 @@ import (
 	"github.com/USTC-vlab/vct/cmd"
 )
 
+var version string = "<unknown>"
+
 func main() {
+	cmd.Version = version
 	if err := cmd.MakeCmd().Execute(); err != nil {
 		os.Exit(1)
 	}