Why does Ruby seem to access files in a directory randomly?

Question

Is this by design?

Here\'s the code:

class FileRenamer
    def RenameFiles(folder_path)    
        files = Dir.glob(folder_path + \"/*\")
    end
en         


        

Answer 1

The answer from Scott is out of date. I ran Dir.glob on Mac OS 10.15.6 Catalina, and the files were not returned in alphabetical order. According to the ruby docs, the ordering is determined by the OS.

https://ruby-doc.org/core-2.5.1/Dir.html

Note that the pattern is not a regexp, it's closer to a shell glob. See File.fnmatch for the meaning of the flags parameter. Case sensitivity depends on your system (File::FNM_CASEFOLD is ignored), as does the order in which the results are returned.

Answer 2

The order should be the same every time on a particular OS, however it is different across operating systems.

The behaviour or Dir.glob can not be relied upon to be the same across different OSs. Not sure if this is by design, but rather an artefact of the filesystems.

On Windows and Linux the results are sorted by hierarchy, and then alphabetically; On Mac OS X the results are sorted alphabetically.

You could mitigate the effect by calling sort on your results e.g.:

files = Dir.glob("./*").sort

or if you wanted it case insensitive, perhaps:

 files = Dir.glob("./*").sort {|a,b| a.upcase <=> b.upcase}