[~] $ perldiag locale
      perl: warning: Setting locale failed.
      (S) The whole warning message will look something like:

              perl: warning: Setting locale failed.
              perl: warning: Please check that your locale settings:
                      LC_ALL = "En_US",
                      LANG = (unset)
                  are supported and installed on your system.
              perl: warning: Falling back to the standard
                             locale ("C").

       Exactly what were the failed locale settings varies.
       In the above the settings were that the LC_ALL was
       "En_US" and the LANG had no value. This error means
       that Perl detected that you and/or your system
       administrator have set up the so-called variable
       system but Perl could not use those settings. This
       was not dead serious, fortunately: there is a
       "default locale" called "C" that Perl can and will
       use, the script will be run. Before you really fix
       the problem, however, you will get the same error
       message each time you run Perl. How to really fix
       the problem can be found in the perllocale manpage
       section LOCALE PROBLEMS.

  [~] $
[download]

perllocale has a whole lot of information on how to solve/fix/mute this issue.

-dlc