M-x helm shows duplicates after upgrading to Emacs 27. Turns out the changed behavior is easily fixed by configuring history-delete-duplicates. Answer courtesy official issue .

With this you can readily search an entire project directory for some text, and then make whole-scale changes to any or all files containing that text. I assume you already have helm-projectile installed and you use it; if not, you’re missing out! First, install wgrep and helm-wgrep, for which I use use-package and my emacs.el init file: (use-package wgrep :ensure t :config (use-package wgrep-helm :ensure t)) Then, execute helm-projectile-grep for the text you desire.