lookup vi from $PATH

cmd/cli.go

@@ -8,6 +8,7 @@ import (
 	"io/ioutil"
 	"local/pt-todo-server/pttodo"
 	"os"
+	"os/exec"
 	"path"
 	"syscall"
 
@@ -52,7 +53,10 @@ func edit(filepath string) error {
 		return nil
 	}
 	vi := func() error {
-		vibin := "/usr/bin/vi"
+		vibin, err := exec.LookPath("vi")
+		if err != nil {
+			return err
+		}
 		cpid, err := syscall.ForkExec(
 			vibin,
 			[]string{vibin, tempFile},