Add early git availability check with clear error message

backup.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"fmt"
 	"log"
 	"net/url"
 	"os/exec"
@@ -16,6 +17,16 @@ var execCommand = exec.Command
 var appFS = afero.NewOsFs()
 var gitCommand = "git"
 var gethomeDir = homedir.Dir
+var lookPath = exec.LookPath
+
+// checkGitAvailability verifies that the git command is available in the system PATH
+func checkGitAvailability() error {
+	_, err := lookPath(gitCommand)
+	if err != nil {
+		return fmt.Errorf("git command not found in PATH. Please install git to use gitbackup. Visit https://git-scm.com/downloads for installation instructions")
+	}
+	return nil
+}
 
 // Check if we have a copy of the repo already, if
 // we do, we update the repo, else we do a fresh clone

backup_test.go

@@ -5,6 +5,7 @@ import (
 	"os"
 	"os/exec"
 	"path"
+	"strings"
 	"sync"
 	"testing"
 
@@ -243,3 +244,38 @@ func TestSetupBackupDir(t *testing.T) {
 		}
 	}
 }
+
+func TestCheckGitAvailability(t *testing.T) {
+	// Save original lookPath
+	originalLookPath := lookPath
+	defer func() {
+		lookPath = originalLookPath
+	}()
+
+	t.Run("git is available", func(t *testing.T) {
+		lookPath = func(file string) (string, error) {
+			if file == "git" {
+				return "/usr/bin/git", nil
+			}
+			return "", fmt.Errorf("not found")
+		}
+		err := checkGitAvailability()
+		if err != nil {
+			t.Errorf("Expected no error, got %v", err)
+		}
+	})
+
+	t.Run("git is not available", func(t *testing.T) {
+		lookPath = func(file string) (string, error) {
+			return "", fmt.Errorf("executable file not found in $PATH")
+		}
+		err := checkGitAvailability()
+		if err == nil {
+			t.Error("Expected error when git is not available, got nil")
+		}
+		expectedMsg := "git command not found in PATH"
+		if err != nil && !strings.HasPrefix(err.Error(), expectedMsg) {
+			t.Errorf("Expected error message to start with '%s', got '%s'", expectedMsg, err.Error())
+		}
+	})
+}

git_repository_clone.go

@@ -9,6 +9,11 @@ import (
 // handleGitRepositoryClone clones or updates all repositories for the configured service
 func handleGitRepositoryClone(client interface{}, c *appConfig) error {
 
+	// Check if git is available before proceeding
+	if err := checkGitAvailability(); err != nil {
+		return err
+	}
+
 	// Used for waiting for all the goroutines to finish before exiting
 	var wg sync.WaitGroup
 	defer wg.Wait()