locale errors during apt-get upgrades

[Tom H]

On Mon, May 20, 2013 at 9:03 AM, Sabniveesu Shashank
<shashank16392 at gmail.com> wrote:
>
> Hi, I've been using Ubuntu since 11.10. Why do I get the following messages
> whenever I update my packages? Why doesn't  Ubuntu itself set them by
> default?
>
> locale: Cannot set LC_CTYPE to default locale: No such file or directory
> locale: Cannot set LC_MESSAGES to default locale: No such file or directory
> locale: Cannot set LC_ALL to default locale: No such file or directory
> perl: warning: Setting locale failed
> perl: warning: Please check that your locale settings:
>             LANGUAGE = (unset),
>             LC_ALL = (unset)
>             LANG = "en_IN.ISO8859-1"
>       are supported and installed on your system.
> perl: warning: Falling back to the standard locale ("C").

What's the output of "locale" and "locale -a"?