diff --git a/cli/Build.go b/cli/Build.go
new file mode 100644
index 0000000..5c7ea6e
--- /dev/null
+++ b/cli/Build.go
@@ -0,0 +1,5 @@
+package cli
+
+func Build(args []string) int {
+	return 0
+}
diff --git a/cli/Help.go b/cli/Help.go
new file mode 100644
index 0000000..464cb35
--- /dev/null
+++ b/cli/Help.go
@@ -0,0 +1,13 @@
+package cli
+
+import (
+	"git.akyoto.dev/cli/q/log"
+)
+
+func Help(args []string) int {
+	log.Error.Println("Usage: q [command] [options]")
+	log.Error.Println("")
+	log.Error.Println("    build [directory]")
+	log.Error.Println("    system")
+	return 1
+}
diff --git a/cli/Main.go b/cli/Main.go
new file mode 100644
index 0000000..d6d43c6
--- /dev/null
+++ b/cli/Main.go
@@ -0,0 +1,18 @@
+package cli
+
+func Main(args []string) int {
+	if len(args) == 0 {
+		return Help(nil)
+	}
+
+	switch args[0] {
+	case "build":
+		return Build(args[1:])
+
+	case "system":
+		return System(args[1:])
+
+	default:
+		return Help(args[1:])
+	}
+}
diff --git a/cli/System.go b/cli/System.go
new file mode 100644
index 0000000..524e0fb
--- /dev/null
+++ b/cli/System.go
@@ -0,0 +1,41 @@
+package cli
+
+import (
+	"os"
+	"runtime"
+
+	"git.akyoto.dev/cli/q/log"
+)
+
+func System(args []string) int {
+	line := "%-19s%s\n"
+
+	// Platform
+	log.Info.Printf(line, "Platform:", runtime.GOOS)
+
+	// Architecture
+	log.Info.Printf(line, "Architecture:", runtime.GOARCH)
+
+	// Go
+	log.Info.Printf(line, "Go:", runtime.Version())
+
+	// Directory
+	directory, err := os.Getwd()
+
+	if err == nil {
+		log.Info.Printf(line, "Directory:", directory)
+	} else {
+		log.Info.Printf(line, "Directory:", err.Error())
+	}
+
+	// Compiler
+	executable, err := os.Executable()
+
+	if err == nil {
+		log.Info.Printf(line, "Compiler:", executable)
+	} else {
+		log.Info.Printf(line, "Compiler:", err.Error())
+	}
+
+	return 0
+}
diff --git a/cli_test.go b/cli_test.go
new file mode 100644
index 0000000..b99942f
--- /dev/null
+++ b/cli_test.go
@@ -0,0 +1,27 @@
+package main_test
+
+import (
+	"testing"
+
+	"git.akyoto.dev/cli/q/cli"
+	"git.akyoto.dev/go/assert"
+)
+
+func TestCLI(t *testing.T) {
+	type cliTest struct {
+		arguments        []string
+		expectedExitCode int
+	}
+
+	tests := []cliTest{
+		{[]string{}, 1},
+		{[]string{"invalid"}, 1},
+		{[]string{"system"}, 0},
+	}
+
+	for _, test := range tests {
+		exitCode := cli.Main(test.arguments)
+		t.Log(test.arguments)
+		assert.Equal(t, exitCode, test.expectedExitCode)
+	}
+}
diff --git a/go.mod b/go.mod
index 2c2b156..e78e48b 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,5 @@
 module git.akyoto.dev/cli/q
 
 go 1.21
+
+require git.akyoto.dev/go/assert v0.1.3
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..9fc2547
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,2 @@
+git.akyoto.dev/go/assert v0.1.3 h1:QwCUbmG4aZYsNk/OuRBz1zWVKmGlDUHhOnnDBfn8Qw8=
+git.akyoto.dev/go/assert v0.1.3/go.mod h1:0GzMaM0eURuDwtGkJJkCsI7r2aUKr+5GmWNTFPgDocM=
diff --git a/log/log.go b/log/log.go
new file mode 100644
index 0000000..395f6ab
--- /dev/null
+++ b/log/log.go
@@ -0,0 +1,14 @@
+package log
+
+import (
+	"log"
+	"os"
+)
+
+var (
+	// Info is used for general info messages.
+	Info = log.New(os.Stdout, "", 0)
+
+	// Error is used for error messages.
+	Error = log.New(os.Stderr, "", 0)
+)
diff --git a/main.go b/main.go
index d2013bb..2a518ef 100644
--- a/main.go
+++ b/main.go
@@ -1,7 +1,11 @@
 package main
 
-import "os"
+import (
+	"os"
+
+	"git.akyoto.dev/cli/q/cli"
+)
 
 func main() {
-	os.Exit(0)
+	os.Exit(cli.Main(os.Args[1:]))
 }
diff --git a/main_test.go b/main_test.go
new file mode 100644
index 0000000..9bf72ae
--- /dev/null
+++ b/main_test.go
@@ -0,0 +1,15 @@
+package main_test
+
+import (
+	"io"
+	"os"
+	"testing"
+
+	"git.akyoto.dev/cli/q/log"
+)
+
+func TestMain(m *testing.M) {
+	log.Info.SetOutput(io.Discard)
+	log.Error.SetOutput(io.Discard)
+	os.Exit(m.Run())
+}