From ac6295491c771c0da2856524b8e7bb39f1f7da72 Mon Sep 17 00:00:00 2001
From: Maxim Belkin <maxim.belkin@gmail.com>
Date: Wed, 12 Aug 2020 08:22:45 -0500
Subject: [PATCH] cmd/cleanup.rb: fix input handling

---
 Library/Homebrew/cmd/cleanup.rb | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Library/Homebrew/cmd/cleanup.rb b/Library/Homebrew/cmd/cleanup.rb
index 510b872f03..66fe520342 100644
--- a/Library/Homebrew/cmd/cleanup.rb
+++ b/Library/Homebrew/cmd/cleanup.rb
@@ -33,6 +33,10 @@ module Homebrew
   def cleanup
     args = cleanup_args.parse
 
+    if args.prune.present? && !Integer(args.prune, exception: false) && args.prune != "all"
+      raise UsageError, "--prune= expects an integer or 'all'."
+    end
+
     cleanup = Cleanup.new(*args.named, dry_run: args.dry_run?, scrub: args.s?, days: args.prune&.to_i)
     if args.prune_prefix?
       cleanup.prune_prefix_symlinks_and_directories