Rewrite login shell register with go

cmd/enable_nix_login_shells/main.go

@@ -0,0 +1,52 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"strings"
+)
+
+// This script requires sudo execution, if it is a reasonable way, including in home.nix may be better
+
+func main() {
+	homePath, ok := os.LookupEnv("HOME")
+	if !ok {
+		log.Fatalf("$HOME is not found")
+	}
+
+	loginAbles := []string{"zsh", "fish"}
+
+	etcShellsBytes, err := os.ReadFile("/etc/shells")
+	if err != nil {
+		log.Fatalf("%v\n", err)
+	}
+
+	etcShells := string(etcShellsBytes)
+	dirty := strings.Clone(etcShells)
+	examplePath := ""
+
+	for _, sh := range loginAbles {
+		shellPath := homePath + "/.nix-profile/bin/" + sh
+		if strings.Contains(etcShells, shellPath) {
+			log.Printf("skip - %s is already registered in /etc/shells\n", shellPath)
+		} else {
+			log.Printf("insert - %s will be registered in /etc/shells\n", shellPath)
+			examplePath = shellPath
+			dirty += fmt.Sprintln(shellPath)
+		}
+	}
+
+	if dirty != etcShells {
+		err = os.WriteFile("/etc/shells", []byte(dirty), os.ModePerm)
+		if err != nil {
+			log.Fatalf("%v\n", err)
+		}
+
+		fmt.Printf(`
+Done! Set one of your favorite shell as follows
+
+chsh -s %s "$(whoami)"
+		`, examplePath)
+	}
+}