1. Insert the string "//xyz" somewhere in a text field that you can observe. 2. Check that running sudo -u www-data php admin/tool/replace/cli/replace.php --search=$'\xfe' --replace=x exits with an "Invalid characters were found in..." error. (The $'\xfe' under Bash creates an invalid UTF-8 character.) 2. Check that running sudo -u www-data php admin/tool/replace/cli/replace.php --search=//xyz --replace=//wxyz exits with a "The replacement is longer than original..." error. 3. Check that sudo -u www-data php admin/tool/replace/cli/replace.php --search=//xyz --replace=//wxyz --shorten prompts for confirmation, and after accepting the warning, finishes with a "Success" message. 4. Check that your inserted "//xyz" has been replaced with "//wxyz". Use your appropriate equivalent for sudo -u www-data as necessary.