diff --git a/doc/_regexp.rdoc b/doc/_regexp.rdoc
index b862c9a49e0594..76ac3a859e5b15 100644
--- a/doc/_regexp.rdoc
+++ b/doc/_regexp.rdoc
@@ -1251,7 +1251,7 @@ the potential vulnerability arising from this is the {regular expression denial-
 
 \Regexp matching can apply an optimization to prevent ReDoS attacks.
 When the optimization is applied, matching time increases linearly (not polynomially or exponentially)
-in relation to the input size, and a ReDoS attach is not possible.
+in relation to the input size, and a ReDoS attack is not possible.
 
 This optimization is applied if the pattern meets these criteria:
 
diff --git a/tool/commit-email.rb b/tool/commit-email.rb
index f738261dcca6cd..c887f8783e9d30 100755
--- a/tool/commit-email.rb
+++ b/tool/commit-email.rb
@@ -121,7 +121,7 @@ def build_diff(path, numstats)
   end
 
   def git_show(revision, format:)
-    git('show', "--pretty=#{format}", '--no-patch', revision).strip
+    git('show', '--no-show-signature', "--pretty=#{format}", '--no-patch', revision).strip
   end
 
   def git(*args)
@@ -180,7 +180,7 @@ def main(repo_path, to, rest)
     args, options = parse(rest)
 
     infos = args.each_slice(3).flat_map do |oldrev, newrev, refname|
-      revisions = IO.popen(['git', 'log', '--reverse', '--pretty=%H', "#{oldrev}^..#{newrev}"], &:read).lines.map(&:strip)
+      revisions = IO.popen(['git', 'log', '--no-show-signature', '--reverse', '--pretty=%H', "#{oldrev}^..#{newrev}"], &:read).lines.map(&:strip)
       revisions[0..-2].zip(revisions[1..-1]).map do |old, new|
         GitInfoBuilder.new(repo_path).build(old, new, refname)
       end
@@ -211,7 +211,7 @@ def b_encode(str)
   end
 
   def make_body(info, viewer_uri:)
-    body = ''
+    body = +''
     body << "#{info.author}\t#{format_time(info.date)}\n"
     body << "\n"
     body << "  New Revision: #{info.revision}\n"
@@ -276,7 +276,6 @@ def modified_dirs(info)
   end
 
   def changed_dirs_info(info, uri)
-    rev = info.revision
     (info.added_dirs.collect do |dir|
        "  Added: #{dir}\n"
      end + info.deleted_dirs.collect do |dir|
@@ -293,14 +292,11 @@ def diff_info(info, uri)
         values.collect do |type, value|
           case type
           when :added
-            command = 'cat'
             rev = "?revision=#{info.revision}&view=markup"
           when :modified, :property_changed
-            command = 'diff'
             prev_revision = (info.revision.is_a?(Integer) ? info.revision - 1 : "#{info.revision}^")
             rev = "?r1=#{info.revision}&r2=#{prev_revision}&diff_format=u"
           when :deleted, :copied
-            command = 'cat'
             rev = ''
           else
             raise "unknown diff type: #{value[:type]}"
@@ -328,7 +324,7 @@ def make_header(to, from, info)
   end
 
   def make_subject(info)
-    subject = ''
+    subject = +''
     subject << "#{info.revision}"
     subject << " (#{info.branch})"
     subject << ': '
diff --git a/tool/test/test_commit_email.rb b/tool/test/test_commit_email.rb
index efd45022be0bab..b948987ed96411 100644
--- a/tool/test/test_commit_email.rb
+++ b/tool/test/test_commit_email.rb
@@ -20,12 +20,11 @@ def setup
     end
 
     @sendmail = File.join(Dir.mktmpdir, 'sendmail')
-    File.write(@sendmail, <<~SENDMAIL)
-      #!/usr/bin/env ruby
-      print #{STDIN_DELIMITER.dump}
-      puts STDIN.read
+    File.write(@sendmail, <<~SENDMAIL, mode: "wx", perm: 0755)
+      #!/bin/sh
+      echo #{STDIN_DELIMITER.chomp.dump}
+      exec cat
     SENDMAIL
-    FileUtils.chmod(0755, @sendmail)
 
     @commit_email = File.expand_path('../../tool/commit-email.rb', __dir__)
   end